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Doi A, Delaney C, Tanner D, Burkhart K, Bell RD. RNA exon editing: Splicing the way to treat human diseases. MOLECULAR THERAPY. NUCLEIC ACIDS 2024; 35:102311. [PMID: 39281698 PMCID: PMC11401238 DOI: 10.1016/j.omtn.2024.102311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 09/18/2024]
Abstract
RNA exon editing is a therapeutic strategy for correcting disease-causing mutations by inducing trans-splicing between a synthetic RNA molecule and an endogenous pre-mRNA target, resulting in functionally restored mRNA and protein. This approach enables the replacement of exons at the kilobase scale, addresses multiple mutations with a single therapy, and maintains native gene expression without changes to DNA. For genes larger than 5 kb, RNA exon editors can be delivered in a single vector despite AAV capacity limitations because only mutated exons need to be replaced. While correcting mutations by trans-splicing has been previously demonstrated, prior attempts were hampered by low efficiency or lack of translation in preclinical models. Advances in synthetic biology, next-generation sequencing, and bioinformatics, with a deeper understanding of mechanisms controlling RNA splicing, have triggered a re-emergence of trans-splicing and the development of new RNA exon editing molecules for treating human disease, including the first application in a clinical trial (this study was registered at ClinicalTrials.gov [NCT06467344]). Here, we provide an overview of RNA splicing, the history of trans-splicing, previously reported therapeutic applications, and how modern advances are enabling the discovery of RNA exon editing molecules for genetic targets unable to be addressed by conventional gene therapy and gene editing approaches.
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Affiliation(s)
- Akiko Doi
- Ascidian Therapeutics, Boston, MA, USA
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2
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Zhang J, Xu X, Deng H, Liu L, Xiang Y, Feng J. Overcoming cancer drug-resistance calls for novel strategies targeting abnormal alternative splicing. Pharmacol Ther 2024; 261:108697. [PMID: 39025436 DOI: 10.1016/j.pharmthera.2024.108697] [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] [Received: 03/02/2024] [Revised: 05/12/2024] [Accepted: 07/15/2024] [Indexed: 07/20/2024]
Abstract
Abnormal gene alternative splicing (AS) events are strongly associated with cancer progression. Here, we summarize AS events that contribute to the development of drug resistance and classify them into three categories: alternative cis-splicing (ACS), alternative trans-splicing (ATS), and alternative back-splicing (ABS). The regulatory mechanisms underlying AS processes through cis-acting regulatory elements and trans-acting factors are comprehensively described, and the distinct functions of spliced variants, including linear spliced variants derived from ACS, chimeric spliced variants arising from ATS, and circRNAs generated through ABS, are discussed. The identification of dysregulated spliced variants, which contribute to drug resistance and hinder effective cancer treatment, suggests that abnormal AS processes may together serve as a precise regulatory mechanism enabling drug-resistant cancer cell survival or, alternatively, represent an evolutionary pathway for cancer cells to adapt to changes in the external environment. Moreover, this review summarizes recent advancements in treatment approaches targeting AS-associated drug resistance, focusing on cis-acting regulatory elements, trans-acting factors, and specific spliced variants. Collectively, gaining an in-depth understanding of the mechanisms underlying aberrant alternative splicing events and developing strategies to target this process hold great promise for overcoming cancer drug resistance.
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Affiliation(s)
- Ji Zhang
- Department of Anesthesiology, The Affiliated Hospital, Southwest Medical University, Luzhou, Sichuan Province 646000, China; Anesthesiology and Critical Care Medicine Key Laboratory of Luzhou, The Affiliated Hospital, Southwest Medical University, Luzhou, Sichuan Province 646000, China
| | - Xinyu Xu
- Department of Anesthesiology, The Affiliated Hospital, Southwest Medical University, Luzhou, Sichuan Province 646000, China; Anesthesiology and Critical Care Medicine Key Laboratory of Luzhou, The Affiliated Hospital, Southwest Medical University, Luzhou, Sichuan Province 646000, China
| | - Hongwei Deng
- Department of Anesthesiology, The Affiliated Hospital, Southwest Medical University, Luzhou, Sichuan Province 646000, China; Anesthesiology and Critical Care Medicine Key Laboratory of Luzhou, The Affiliated Hospital, Southwest Medical University, Luzhou, Sichuan Province 646000, China
| | - Li Liu
- Department of Anesthesiology, The Affiliated Hospital, Southwest Medical University, Luzhou, Sichuan Province 646000, China; Anesthesiology and Critical Care Medicine Key Laboratory of Luzhou, The Affiliated Hospital, Southwest Medical University, Luzhou, Sichuan Province 646000, China
| | - Yuancai Xiang
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Southwest Medical University, Luzhou city, Sichuan 646000, China.
| | - Jianguo Feng
- Department of Anesthesiology, The Affiliated Hospital, Southwest Medical University, Luzhou, Sichuan Province 646000, China; Anesthesiology and Critical Care Medicine Key Laboratory of Luzhou, The Affiliated Hospital, Southwest Medical University, Luzhou, Sichuan Province 646000, China; Nucleic Acid Medicine of Luzhou Key Laboratory, Southwest Medical University, Luzhou, Sichuan Province 646000, China.
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3
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Cong J, Zhang S, Zhang Q, Yu X, Huang J, Wei X, Huang X, Qiu J, Zhou X. Conserved features and diversity attributes of chimeric RNAs across accessions in four plants. PLANT BIOTECHNOLOGY JOURNAL 2024. [PMID: 39087631 DOI: 10.1111/pbi.14437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Revised: 06/17/2024] [Accepted: 07/08/2024] [Indexed: 08/02/2024]
Abstract
As a non-collinear expression form of genetic information, chimeric RNAs increase the complexity of transcriptome in diverse organisms. Although chimeric RNAs have been identified in plants, few common features have been revealed. Here, we systemically explored the landscape of chimeric RNAs across multi-accession and multi-tissue using pan-genome and transcriptome data of four plants: rice, maize, soybean, and Arabidopsis. Among the four species, conserved characteristics of breakpoints and parental genes were discovered. In each species, chimeric RNAs displayed a high level of diversity among accessions, and the clustering of accessions using chimeric events was generally concordant with clustering based on genomic variants, implying a general relationship between genetic variations and chimeric RNAs. Through mass spectrometry, we confirmed a fusion protein OsNDC1-OsGID1L2 and observed its subcellular localization, which differed from the original proteins. Phenotypic cues in transgenic rice suggest the potential functions of OsNDC1-OsGID1L2. Moreover, an intriguing chimeric event Os01g0216500-Os01g0216900, generated by a large deletion in basmati rice, also exists in another accession without the deletion, demonstrating its convergence in evolution. Our results illuminate the characteristics and hint at the evolutionary implications of plant chimeric RNAs, which serve as a supplement to genetic variations, thus expanding our understanding of genetic diversity.
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Affiliation(s)
- Jia Cong
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Sinan Zhang
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
- CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Qi Zhang
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Xiting Yu
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Jiazhi Huang
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Xin Wei
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Xuehui Huang
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Jie Qiu
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Xiaoyi Zhou
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
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4
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Yokomori R, Kusakabe TG, Nakai K. Characterization of trans-spliced chimeric RNAs: insights into the mechanism of trans-splicing. NAR Genom Bioinform 2024; 6:lqae067. [PMID: 38846348 PMCID: PMC11155486 DOI: 10.1093/nargab/lqae067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 05/13/2024] [Accepted: 05/23/2024] [Indexed: 06/09/2024] Open
Abstract
Trans-splicing is a post-transcriptional processing event that joins exons from separate RNAs to produce a chimeric RNA. However, the detailed mechanism of trans-splicing remains poorly understood. Here, we characterize trans-spliced genes and provide insights into the mechanism of trans-splicing in the tunicate Ciona. Tunicates are the closest invertebrates to humans, and their genes frequently undergo trans-splicing. Our analysis revealed that, in genes that give rise to both trans-spliced and non-trans-spliced messenger RNAs, trans-splice acceptor sites were preferentially located at the first functional acceptor site, and their paired donor sites were weak in both Ciona and humans. Additionally, we found that Ciona trans-spliced genes had GU- and AU-rich 5' transcribed regions. Our data and findings not only are useful for Ciona research community, but may also aid in a better understanding of the trans-splicing mechanism, potentially advancing the development of gene therapy based on trans-splicing.
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Affiliation(s)
- Rui Yokomori
- Human Genome Center, Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
| | - Takehiro G Kusakabe
- Institute for Integrative Neurobiology, Graduate School of Natural Science, Konan University, Kobe 658-8501, Japan
- Department of Biology, Faculty of Science and Engineering, Konan University, Kobe 658-8501, Japan
| | - Kenta Nakai
- Human Genome Center, Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
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Zhang W, Zhang X, Zhan X, Bai R, Lei J, Yan C, Shi Y. Structural insights into human exon-defined spliceosome prior to activation. Cell Res 2024; 34:428-439. [PMID: 38658629 PMCID: PMC11143319 DOI: 10.1038/s41422-024-00949-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Accepted: 03/01/2024] [Indexed: 04/26/2024] Open
Abstract
Spliceosome is often assembled across an exon and undergoes rearrangement to span a neighboring intron. Most states of the intron-defined spliceosome have been structurally characterized. However, the structure of a fully assembled exon-defined spliceosome remains at large. During spliceosome assembly, the pre-catalytic state (B complex) is converted from its precursor (pre-B complex). Here we report atomic structures of the exon-defined human spliceosome in four sequential states: mature pre-B, late pre-B, early B, and mature B. In the previously unknown late pre-B state, U1 snRNP is already released but the remaining proteins are still in the pre-B state; unexpectedly, the RNAs are in the B state, with U6 snRNA forming a duplex with 5'-splice site and U5 snRNA recognizing the 3'-end of the exon. In the early and mature B complexes, the B-specific factors are stepwise recruited and specifically recognize the exon 3'-region. Our study reveals key insights into the assembly of the exon-defined spliceosomes and identifies mechanistic steps of the pre-B-to-B transition.
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Affiliation(s)
- Wenyu Zhang
- Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Xiaofeng Zhang
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China
- Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang, China
| | - Xiechao Zhan
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China
- Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang, China
| | - Rui Bai
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China
- Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang, China
| | - Jianlin Lei
- Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Chuangye Yan
- Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China.
| | - Yigong Shi
- Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China.
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China.
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China.
- Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang, China.
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Ying R, Li C, Li H, Zou J, Hu M, Hong Q, Shen Y, Hou L, Cheng H, Zhou R. RPGR is a guanine nucleotide exchange factor for the small GTPase RAB37 required for retinal function via autophagy regulation. Cell Rep 2024; 43:114010. [PMID: 38536817 DOI: 10.1016/j.celrep.2024.114010] [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] [Received: 07/26/2023] [Revised: 01/28/2024] [Accepted: 03/13/2024] [Indexed: 04/28/2024] Open
Abstract
Although the small GTPase RAB37 acts as an organizer of autophagosome biogenesis, the upstream regulatory mechanism of autophagy via guanosine diphosphate (GDP)-guanosine triphosphate (GTP) exchange in maintaining retinal function has not been determined. We found that retinitis pigmentosa GTPase regulator (RPGR) is a guanine nucleotide exchange factor that activates RAB37 by accelerating GDP-to-GTP exchange. RPGR directly interacts with RAB37 via the RPGR-RCC1-like domain to promote autophagy through stimulating exchange. Rpgr knockout (KO) in mice leads to photoreceptor degeneration owing to autophagy impairment in the retina. Notably, the retinopathy phenotypes of Rpgr KO retinas are rescued by the adeno-associated virus-mediated transfer of pre-trans-splicing molecules, which produce normal Rpgr mRNAs via trans-splicing in the Rpgr KO retinas. This rescue upregulates autophagy through the re-expression of RPGR in KO retinas to accelerate GDP-to-GTP exchange; thus, retinal homeostasis reverts to normal. Taken together, these findings provide an important missing link for coordinating RAB37 GDP-GTP exchange via the RPGR and retinal homeostasis by autophagy regulation.
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Affiliation(s)
- Ruhong Ying
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China
| | - Cong Li
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China
| | - Huirong Li
- State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou 325003, China
| | - Juan Zou
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China
| | - Mengxin Hu
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China
| | - Qiang Hong
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China
| | - Yin Shen
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China
| | - Ling Hou
- State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou 325003, China.
| | - Hanhua Cheng
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China.
| | - Rongjia Zhou
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China.
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7
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Speakman E, Gunaratne GH. On a kneading theory for gene-splicing. CHAOS (WOODBURY, N.Y.) 2024; 34:043125. [PMID: 38579148 DOI: 10.1063/5.0199364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Accepted: 03/05/2024] [Indexed: 04/07/2024]
Abstract
Two well-known facets in protein synthesis in eukaryotic cells are transcription of DNA to pre-RNA in the nucleus and the translation of messenger-RNA (mRNA) to proteins in the cytoplasm. A critical intermediate step is the removal of segments (introns) containing ∼97% of the nucleic-acid sites in pre-RNA and sequential alignment of the retained segments (exons) to form mRNA through a process referred to as splicing. Alternative forms of splicing enrich the proteome while abnormal splicing can enhance the likelihood of a cell developing cancer or other diseases. Mechanisms for splicing and origins of splicing errors are only partially deciphered. Our goal is to determine if rules on splicing can be inferred from data analytics on nucleic-acid sequences. Toward that end, we represent a nucleic-acid site as a point in a plane defined in terms of the anterior and posterior sub-sequences of the site. The "point-set" representation expands analytical approaches, including the use of statistical tools, to characterize genome sequences. It is found that point-sets for exons and introns are visually different, and that the differences can be quantified using a family of generalized moments. We design a machine-learning algorithm that can recognize individual exons or introns with 91% accuracy. Point-set distributions and generalized moments are found to differ between organisms.
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Affiliation(s)
- Ethan Speakman
- Department of Physics, University of Houston, Houston, Texas 77204, USA
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8
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López-Pérez M, Aguirre-Garrido F, Herrera-Zúñiga L, Fernández FJ. Gene as a dynamical notion: An extensive and integrative vision. Redefining the gene concept, from traditional to genic-interaction, as a new dynamical version. Biosystems 2023; 234:105060. [PMID: 37844827 DOI: 10.1016/j.biosystems.2023.105060] [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] [Received: 04/27/2023] [Revised: 09/08/2023] [Accepted: 10/10/2023] [Indexed: 10/18/2023]
Abstract
The current concept of gene has been very useful during the 20th and 21st centuries. However, recent advances in molecular biology and bioinformatics, which have further diversified the functional and adaptive profile of genetic information and its integration with cell physiology and environmental response, have contributed to focusing on additional new gene properties besides the traditional definition. Considering the inherent complexity of gene expression, whose adaptive objective must be referred to the Tortoise-Hare model, in which two tendencies converge, one focused on rapid adaptation to achieve survival, and the other that prevents an over-adaptation effect. In this context, a revision of the gene concept must be made, which must include these new mechanisms and approaches. In this paper, we propose a new conception of the idea of a gene that moves from a static and defined version of hereditary information to a dynamic idea that preponderates gene interaction (circumscribed to that established between protein-protein, protein-nucleic acid, and nucleic acid-nucleic acid) and the selection it exerts, as the irreducible element that works in a coordinated way in a genomic regulatory network (GRN).
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Affiliation(s)
- Marcos López-Pérez
- Environmental Sciences Department, Universidad Autónoma Metropolitana (Lerma Unit) Av. de las Garzas N° 10, Col. El Panteón, Municipio de Lerma de Villada, Estado de México, C.P. 52005, Mexico.
| | - Félix Aguirre-Garrido
- Environmental Sciences Department, Universidad Autónoma Metropolitana (Lerma Unit) Av. de las Garzas N° 10, Col. El Panteón, Municipio de Lerma de Villada, Estado de México, C.P. 52005, Mexico
| | - Leonardo Herrera-Zúñiga
- Chemistry Department, Universidad Autónoma Metropolitana (Iztapalapa Unit), C.P. 09340, Mexico City, Mexico
| | - Francisco J Fernández
- Biotechnology Department, Universidad Autónoma Metropolitana (Iztapalapa Unit), C.P. 09340, Mexico City, Mexico.
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Seabolt MH, Roellig DM, Konstantinidis KT. Spliceosomal introns in the diplomonad parasite Giardia duodenalis revisited. Microb Genom 2023; 9. [PMID: 37934076 DOI: 10.1099/mgen.0.001117] [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: 11/08/2023] Open
Abstract
Complete reference genomes, including correct feature annotations, are a fundamental aspect of genomic biology. In the case of protozoan species such as Giardia duodenalis, a major human and animal parasite worldwide, accurate genome annotation can deepen our understanding of the evolution of parasitism and pathogenicity by identifying genes underlying key traits and clinically relevant cellular mechanisms, and by extension, the development of improved prevention strategies and treatments. This study used bioinformatics analyses of Giardia mRNA libraries to characterize known introns and identify new intron candidates, working towards completion of the G. duodenalis assemblage A strain 'WB' genome and further elucidating Giardia's gene expression. By using a set of experimentally validated positive control loci to calibrate our intron detection pipeline, we were able to detect evidence of previously missed candidate splice junctions directly from expressed transcript data. These intron candidates were further studied in silico using NMDS (non-metric multidimensional scaling) clustering to determine shared characteristics and their relative importance such as secondary structure, splicing efficiency and motif conservation, and thus to refine intron models. Results from this study identified 34 new intron candidates, with several potential introns showing evidence that secondary structure of the mRNA molecule might play a more significant role in splicing than previously reported eukaryotic splicing activity mediated by a reduced spliceosome present in G. duodenalis.
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Affiliation(s)
- Matthew H Seabolt
- Division of Foodborne, Waterborne, and Environmental Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
- Leidos Inc., Reston, VA 20190, USA
| | - Dawn M Roellig
- Division of Foodborne, Waterborne, and Environmental Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - Konstantinos T Konstantinidis
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
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10
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Bornstein K, Gryan G, Chang ES, Marchler-Bauer A, Schneider VA. The NIH Comparative Genomics Resource: addressing the promises and challenges of comparative genomics on human health. BMC Genomics 2023; 24:575. [PMID: 37759191 PMCID: PMC10523801 DOI: 10.1186/s12864-023-09643-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Accepted: 08/31/2023] [Indexed: 09/29/2023] Open
Abstract
Comparative genomics is the comparison of genetic information within and across organisms to understand the evolution, structure, and function of genes, proteins, and non-coding regions (Sivashankari and Shanmughavel, Bioinformation 1:376-8, 2007). Advances in sequencing technology and assembly algorithms have resulted in the ability to sequence large genomes and provided a wealth of data that are being used in comparative genomic analyses. Comparative analysis can be leveraged to systematically explore and evaluate the biological relationships and evolution between species, aid in understanding the structure and function of genes, and gain a better understanding of disease and potential drug targets. As our knowledge of genetics expands, comparative genomics can help identify emerging model organisms among a broader span of the tree of life, positively impacting human health. This impact includes, but is not limited to, zoonotic disease research, therapeutics development, microbiome research, xenotransplantation, oncology, and toxicology. Despite advancements in comparative genomics, new challenges have arisen around the quantity, quality assurance, annotation, and interoperability of genomic data and metadata. New tools and approaches are required to meet these challenges and fulfill the needs of researchers. This paper focuses on how the National Institutes of Health (NIH) Comparative Genomics Resource (CGR) can address both the opportunities for comparative genomics to further impact human health and confront an increasingly complex set of challenges facing researchers.
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Affiliation(s)
| | - Gary Gryan
- The MITRE Corporation, 7525 Colshire Dr, McLean, VA, USA
| | - E Sally Chang
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, 20894, USA
| | - Aron Marchler-Bauer
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, 20894, USA
| | - Valerie A Schneider
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, 20894, USA.
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11
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Chen YC, Chen CY, Chiang TW, Chan MH, Hsiao M, Ke HM, Tsai I, Chuang TJ. Detecting intragenic trans-splicing events from non-co-linearly spliced junctions by hybrid sequencing. Nucleic Acids Res 2023; 51:7777-7797. [PMID: 37497782 PMCID: PMC10450196 DOI: 10.1093/nar/gkad623] [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: 05/02/2022] [Accepted: 07/14/2023] [Indexed: 07/28/2023] Open
Abstract
Trans-spliced RNAs (ts-RNAs) are a type of non-co-linear (NCL) transcripts that consist of exons in an order topologically inconsistent with the corresponding DNA template. Detecting ts-RNAs is often interfered by experimental artifacts, circular RNAs (circRNAs) and genetic rearrangements. Particularly, intragenic ts-RNAs, which are derived from separate precursor mRNA molecules of the same gene, are often mistaken for circRNAs through analyses of RNA-seq data. Here we developed a bioinformatics pipeline (NCLscan-hybrid), which integrated short and long RNA-seq reads to minimize false positives and proposed out-of-circle and rolling-circle long reads to distinguish between intragenic ts-RNAs and circRNAs. Combining NCLscan-hybrid screening and multiple experimental validation steps successfully confirmed that four NCL events, which were previously regarded as circRNAs in databases, originated from trans-splicing. CRISPR-based endogenous genome modification experiments further showed that flanking intronic complementary sequences can significantly contribute to ts-RNA formation, providing an efficient/specific method to deplete ts-RNAs. We also experimentally validated that one ts-RNA (ts-ARFGEF1) played an important role for p53-mediated apoptosis through affecting the PERK/eIF2a/ATF4/CHOP signaling pathway in breast cancer cells. This study thus described both bioinformatics procedures and experimental validation steps for rigorous characterization of ts-RNAs, expanding future studies for identification, biogenesis, and function of these important but understudied transcripts.
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Affiliation(s)
- Yu-Chen Chen
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Chia-Ying Chen
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Tai-Wei Chiang
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Ming-Hsien Chan
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
- Department of Biomedical Imaging and Radiological Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Michael Hsiao
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Huei-Mien Ke
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
- Department of Microbiology, Soochow University, Taipei, Taiwan
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12
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Bernard F, Dargère D, Rechavi O, Dupuy D. Quantitative analysis of C. elegans transcripts by Nanopore direct-cDNA sequencing reveals terminal hairpins in non trans-spliced mRNAs. Nat Commun 2023; 14:1229. [PMID: 36869073 PMCID: PMC9984361 DOI: 10.1038/s41467-023-36915-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 02/23/2023] [Indexed: 03/05/2023] Open
Abstract
In nematodes and kinetoplastids, mRNA processing involves a trans-splicing step through which a short sequence from a snRNP replaces the original 5' end of the primary transcript. It has long been held that 70% of C. elegans mRNAs are submitted to trans-splicing. Our recent work suggested that the mechanism is more pervasive but not fully captured by mainstream transcriptome sequencing methods. Here we use Oxford Nanopore's long-read amplification-free sequencing technology to perform a comprehensive analysis of trans-splicing in worms. We demonstrate that spliced leader (SL) sequences at the 5' end of the mRNAs affect library preparation and generate sequencing artefacts due to their self-complementarity. Consistent with our previous observations, we find evidence of trans-splicing for most genes. However, a subset of genes appears to be only marginally trans-spliced. These mRNAs all share the capacity to generate a 5' terminal hairpin structure mimicking the SL structure and offering a mechanistic explanation for their non conformity. Altogether, our data provide a comprehensive quantitative analysis of SL usage in C. elegans.
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Affiliation(s)
- Florian Bernard
- Université de Bordeaux, Inserm U1212, CNRS UMR5320, Institut Européen de Chimie et Biologie (IECB), 2, rue Robert Escarpit, 33607, Pessac, France.,Department of Neurobiology, Wise Faculty of Life Sciences & Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Delphine Dargère
- Université de Bordeaux, Inserm U1212, CNRS UMR5320, Institut Européen de Chimie et Biologie (IECB), 2, rue Robert Escarpit, 33607, Pessac, France
| | - Oded Rechavi
- Department of Neurobiology, Wise Faculty of Life Sciences & Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Denis Dupuy
- Université de Bordeaux, Inserm U1212, CNRS UMR5320, Institut Européen de Chimie et Biologie (IECB), 2, rue Robert Escarpit, 33607, Pessac, France.
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13
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Trans-splicing in the cestode Hymenolepis microstoma is constitutive across the life cycle and depends on gene structure and composition. Int J Parasitol 2023; 53:103-117. [PMID: 36621599 DOI: 10.1016/j.ijpara.2022.11.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 10/31/2022] [Accepted: 11/10/2022] [Indexed: 01/07/2023]
Abstract
Spliced leader (SL) trans-splicing is a key process during mRNA maturation of many eukaryotes, in which a short sequence (SL) is transferred from a precursor SL-RNA into the 5' region of an immature mRNA. This mechanism is present in flatworms, in which it is known to participate in the resolution of polycistronic transcripts. However, most trans-spliced transcripts are not part of operons, and it is not clear if this process may participate in additional regulatory mechanisms in this group. In this work, we present a comprehensive analysis of SL trans-splicing in the model cestode Hymenolepis microstoma. We identified four different SL-RNAs which are indiscriminately trans-spliced to 622 gene models. SL trans-splicing is enriched in constitutively expressed genes and does not appear to be regulated throughout the life cycle. Operons represented at least 20% of all detected trans-spliced gene models, showed conservation to those of the cestode Echinococcus multilocularis, and included complex loci such as an alternative operon (processed as either a single gene through cis-splicing or as two genes of a polycistron). Most insertion sites were identified in the 5' untranslated region (UTR) of monocistronic genes. These genes frequently contained introns in the 5' UTR, in which trans-splicing used the same acceptor sites as cis-splicing. These results suggest that, unlike other eukaryotes, trans-splicing is associated with internal intronic promoters in the 5' UTR, resulting in transcripts with strong splicing acceptor sites without competing cis-donor sites, pointing towards a simple mechanism driving the evolution of novel SL insertion sites.
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14
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Marrone L, Marchi PM, Azzouz M. Circumventing the packaging limit of AAV-mediated gene replacement therapy for neurological disorders. Expert Opin Biol Ther 2022; 22:1163-1176. [PMID: 34904932 DOI: 10.1080/14712598.2022.2012148] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 11/25/2021] [Indexed: 12/19/2022]
Abstract
INTRODUCTION Gene therapy provides the exciting opportunity of a curative single treatment for devastating diseases, eradicating the need for chronic medication. Adeno-associated viruses (AAVs) are among the most attractive vector carriers for gene replacement in vivo. Yet, despite the success of recent AAV-based clinical trials, the clinical use of these vectors has been limited. For instance, the AAV packaging capacity is restricted to ~4.7 kb, making it a substantial challenge to deliver large gene products. AREAS COVERED In this review, we explore established and emerging strategies that circumvent the packaging limit of AAVs to make them effective vehicles for gene replacement therapy of monogenic disorders, with a particular focus on diseases affecting the nervous system. We report historical references, design remarks, as well as strengths and weaknesses of these approaches. We additionally discuss examples of neurological disorders for which such strategies have been attempted. EXPERT OPINION The field of AAV-gene therapy has experienced enormous advancements in the last decade. However, there is still ample space for improvement aimed at overcoming existing challenges that are slowing down the progressive trajectory of this field.
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Affiliation(s)
- Lara Marrone
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield, UK
| | - Paolo M Marchi
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield, UK
| | - Mimoun Azzouz
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield, UK
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15
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Lukas P, Melikian G, Hildebrandt JP, Müller C. Make it double: identification and characterization of a Tandem-Hirudin from the Asian medicinal leech Hirudinaria manillensis. Parasitol Res 2022; 121:2995-3006. [PMID: 36006484 PMCID: PMC9464118 DOI: 10.1007/s00436-022-07634-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 08/19/2022] [Indexed: 11/30/2022]
Abstract
Haematophagous leeches express a broad variety of secretory proteins in their salivary glands, among them are hirudins and hirudin-like factors. Here, we describe the identification, molecular and initial functional characterization of Tandem-Hirudin (TH), a novel salivary gland derived factor identified in the Asian medicinal leech, Hirudinaria manillensis. In contrast to the typical structure of hirudins, TH comprises two globular domains arranged in a tandem-like orientation and lacks the elongated C-terminal tail. Similar structures of thrombin inhibitors have so far been identified only in kissing bugs and ticks. Expression of TH was performed in both cell-based and cell-free bacterial systems. A subsequent functional characterization revealed no evidence for a thrombin-inhibitory potency of TH.
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Affiliation(s)
- Phil Lukas
- Animal Physiology, Zoological Institute and Museum, University of Greifswald, Felix-Hausdorff-Str. 1, D-17489, Greifswald, Germany
| | - Georgij Melikian
- Animal Physiology, Zoological Institute and Museum, University of Greifswald, Felix-Hausdorff-Str. 1, D-17489, Greifswald, Germany
| | - Jan-Peter Hildebrandt
- Animal Physiology, Zoological Institute and Museum, University of Greifswald, Felix-Hausdorff-Str. 1, D-17489, Greifswald, Germany
| | - Christian Müller
- Animal Physiology, Zoological Institute and Museum, University of Greifswald, Felix-Hausdorff-Str. 1, D-17489, Greifswald, Germany.
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16
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Sun Y, Li H. Chimeric RNAs Discovered by RNA Sequencing and Their Roles in Cancer and Rare Genetic Diseases. Genes (Basel) 2022; 13:genes13050741. [PMID: 35627126 PMCID: PMC9140685 DOI: 10.3390/genes13050741] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 04/13/2022] [Accepted: 04/20/2022] [Indexed: 12/30/2022] Open
Abstract
Chimeric RNAs are transcripts that are generated by gene fusion and intergenic splicing events, thus comprising nucleotide sequences from different parental genes. In the past, Northern blot analysis and RT-PCR were used to detect chimeric RNAs. However, they are low-throughput and can be time-consuming, labor-intensive, and cost-prohibitive. With the development of RNA-seq and transcriptome analyses over the past decade, the number of chimeric RNAs in cancer as well as in rare inherited diseases has dramatically increased. Chimeric RNAs may be potential diagnostic biomarkers when they are specifically expressed in cancerous cells and/or tissues. Some chimeric RNAs can also play a role in cell proliferation and cancer development, acting as tools for cancer prognosis, and revealing new insights into the cell origin of tumors. Due to their abilities to characterize a whole transcriptome with a high sequencing depth and intergenically identify spliced chimeric RNAs produced with the absence of chromosomal rearrangement, RNA sequencing has not only enhanced our ability to diagnose genetic diseases, but also provided us with a deeper understanding of these diseases. Here, we reviewed the mechanisms of chimeric RNA formation and the utility of RNA sequencing for discovering chimeric RNAs in several types of cancer and rare inherited diseases. We also discussed the diagnostic, prognostic, and therapeutic values of chimeric RNAs.
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Affiliation(s)
- Yunan Sun
- Department of Pathology, School of Medicine, University of Virginia, Charlottesville, VA 22908, USA;
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Virginia, Charlottesville, VA 22908, USA
| | - Hui Li
- Department of Pathology, School of Medicine, University of Virginia, Charlottesville, VA 22908, USA;
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Virginia, Charlottesville, VA 22908, USA
- Correspondence:
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17
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Peng Y, Ai X, Peng B. Trans-cleaving hammerhead ribozyme in specific regions can improve knockdown efficiency in vivo. J Cell Biochem 2022. [PMID: 35411616 DOI: 10.1002/jcb.30249] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 03/06/2022] [Accepted: 03/28/2022] [Indexed: 11/08/2022]
Abstract
Trans-cleaving techniques have been most enthusiastically embraced in the development of therapy for genetic diseases, particularly in the correction of monogenic recessive mutations at the messenger RNA level. However, easy degradation and poor catalytic activity in vivo remain significant obstacles to trans-cleaving of the hammerhead ribozyme. Herein, we found a novel scaffold RNA that stabilizes the ribozyme structure in trans-cleaving and promotes the knockdown efficiency of the hammerhead ribozyme in specific regions of living cells. We can give the trans-cleaving hammerhead ribozyme the ability to knock down specific genes in specific cell regions by changing different scaffolds. Therefore, our study proves the potential usefulness of the RNA knockdown strategy with high-specific trans-cleaving hammerhead ribozyme as a therapeutic approach in gene therapy.
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Affiliation(s)
- Yan Peng
- Medical School, Fuyang Normal University, Fuyang, Anhui, China
- Natural Products Research Center, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, Sichuan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xilei Ai
- Natural Products Research Center, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, Sichuan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Bo Peng
- College of Life Science and Resources and Environment, Yichun University, Yichun, Jiangxi, China
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18
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Pitolli C, Marini A, Sette C, Pagliarini V. Non-Canonical Splicing and Its Implications in Brain Physiology and Cancer. Int J Mol Sci 2022; 23:ijms23052811. [PMID: 35269953 PMCID: PMC8911335 DOI: 10.3390/ijms23052811] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 02/28/2022] [Accepted: 03/02/2022] [Indexed: 02/01/2023] Open
Abstract
The advance of experimental and computational techniques has allowed us to highlight the existence of numerous different mechanisms of RNA maturation, which have been so far unknown. Besides canonical splicing, consisting of the removal of introns from pre-mRNA molecules, non-canonical splicing events may occur to further increase the regulatory and coding potential of the human genome. Among these, splicing of microexons, recursive splicing and biogenesis of circular and chimeric RNAs through back-splicing and trans-splicing processes, respectively, all contribute to expanding the repertoire of RNA transcripts with newly acquired regulatory functions. Interestingly, these non-canonical splicing events seem to occur more frequently in the central nervous system, affecting neuronal development and differentiation programs with important implications on brain physiology. Coherently, dysregulation of non-canonical RNA processing events is associated with brain disorders, including brain tumours. Herein, we summarize the current knowledge on molecular and regulatory mechanisms underlying canonical and non-canonical splicing events with particular emphasis on cis-acting elements and trans-acting factors that all together orchestrate splicing catalysis reactions and decisions. Lastly, we review the impact of non-canonical splicing on brain physiology and pathology and how unconventional splicing mechanisms may be targeted or exploited for novel therapeutic strategies in cancer.
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Affiliation(s)
- Consuelo Pitolli
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, 00168 Rome, Italy; (C.P.); (C.S.)
- GSTEP-Organoids Research Core Facility, IRCCS Fondazione Policlinico Universitario Agostino Gemelli, 00168 Rome, Italy;
| | - Alberto Marini
- GSTEP-Organoids Research Core Facility, IRCCS Fondazione Policlinico Universitario Agostino Gemelli, 00168 Rome, Italy;
| | - Claudio Sette
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, 00168 Rome, Italy; (C.P.); (C.S.)
- GSTEP-Organoids Research Core Facility, IRCCS Fondazione Policlinico Universitario Agostino Gemelli, 00168 Rome, Italy;
| | - Vittoria Pagliarini
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, 00168 Rome, Italy; (C.P.); (C.S.)
- GSTEP-Organoids Research Core Facility, IRCCS Fondazione Policlinico Universitario Agostino Gemelli, 00168 Rome, Italy;
- Correspondence:
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19
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Falzarano MS, Grilli A, Zia S, Fang M, Rossi R, Gualandi F, Rimessi P, El Dani R, Fabris M, Lu Z, Li W, Mongini T, Ricci F, Pegoraro E, Bello L, Barp A, Sansone VA, Hegde M, Roda B, Reschiglian P, Bicciato S, Selvatici R, Ferlini A. RNA-seq in DMD urinary stem cells recognized muscle-related transcription signatures and addressed the identification of atypical mutations by whole-genome sequencing. HGG ADVANCES 2022; 3:100054. [PMID: 35047845 PMCID: PMC8756543 DOI: 10.1016/j.xhgg.2021.100054] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 08/18/2021] [Indexed: 12/13/2022] Open
Abstract
Urinary stem cells (USCs) are a non-invasive, simple, and affordable cell source to study human diseases. Here we show that USCs are a versatile tool for studying Duchenne muscular dystrophy (DMD), since they are able to address RNA signatures and atypical mutation identification. Gene expression profiling of DMD individuals' USCs revealed a profound deregulation of inflammation, muscle development, and metabolic pathways that mirrors the known transcriptional landscape of DMD muscle and worsens following USCs' myogenic transformation. This pathogenic transcription signature was reverted by an exon-skipping corrective approach, suggesting the utility of USCs in monitoring DMD antisense therapy. The full DMD transcript profile performed in USCs from three undiagnosed DMD individuals addressed three splicing abnormalities, which were decrypted and confirmed as pathogenic variations by whole-genome sequencing (WGS). This combined genomic approach allowed the identification of three atypical and complex DMD mutations due to a deep intronic variation and two large inversions, respectively. All three mutations affect DMD gene splicing and cause a lack of dystrophin protein production, and one of these also generates unique fusion genes and transcripts. Further characterization of USCs using a novel cell-sorting technology (Celector) highlighted cell-type variability and the representation of cell-specific DMD isoforms. Our comprehensive approach to USCs unraveled RNA, DNA, and cell-specific features and demonstrated that USCs are a robust tool for studying and diagnosing DMD.
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Affiliation(s)
- Maria S Falzarano
- Department of Medical Sciences, Unit of Medical Genetics, University of Ferrara, Ferrara 44121, Italy
| | - Andrea Grilli
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena 41121, Italy
| | | | | | - Rachele Rossi
- Department of Medical Sciences, Unit of Medical Genetics, University of Ferrara, Ferrara 44121, Italy
| | - Francesca Gualandi
- Department of Medical Sciences, Unit of Medical Genetics, University of Ferrara, Ferrara 44121, Italy
| | - Paola Rimessi
- Department of Medical Sciences, Unit of Medical Genetics, University of Ferrara, Ferrara 44121, Italy
| | - Reem El Dani
- Department of Medical Sciences, Unit of Medical Genetics, University of Ferrara, Ferrara 44121, Italy
| | - Marina Fabris
- Department of Medical Sciences, Unit of Medical Genetics, University of Ferrara, Ferrara 44121, Italy
| | | | - Wenyan Li
- BGI-Shenzhen, Shenzhen 518083, China
| | | | | | - Elena Pegoraro
- ERN Neuromuscular Center, Department of Neurosciences, Unit of Neurology, University of Padua, Padua 35122, Italy
| | - Luca Bello
- ERN Neuromuscular Center, Department of Neurosciences, Unit of Neurology, University of Padua, Padua 35122, Italy
| | - Andrea Barp
- The NEMO Clinical Center, Neurorehabilitation Unit, University of Milan, Milan 20162, Italy
| | - Valeria A Sansone
- The NEMO Clinical Center, Neurorehabilitation Unit, University of Milan, Milan 20162, Italy
| | - Madhuri Hegde
- PerkinElmer Genomics, 3950 Shackleford Rd., Ste. 195, Duluth, GA 30096, USA
| | - Barbara Roda
- Stem Sel s.r.l., Bologna 40127, Italy
- Department of Chemistry "G. Ciamician," University of Bologna, Bologna 40126, Italy
| | - Pierluigi Reschiglian
- Stem Sel s.r.l., Bologna 40127, Italy
- Department of Chemistry "G. Ciamician," University of Bologna, Bologna 40126, Italy
| | - Silvio Bicciato
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena 41121, Italy
| | - Rita Selvatici
- Department of Medical Sciences, Unit of Medical Genetics, University of Ferrara, Ferrara 44121, Italy
| | - Alessandra Ferlini
- Department of Medical Sciences, Unit of Medical Genetics, University of Ferrara, Ferrara 44121, Italy
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20
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Davidson NM, Chen Y, Sadras T, Ryland GL, Blombery P, Ekert PG, Göke J, Oshlack A. JAFFAL: detecting fusion genes with long-read transcriptome sequencing. Genome Biol 2022; 23:10. [PMID: 34991664 PMCID: PMC8739696 DOI: 10.1186/s13059-021-02588-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 12/22/2021] [Indexed: 12/26/2022] Open
Abstract
In cancer, fusions are important diagnostic markers and targets for therapy. Long-read transcriptome sequencing allows the discovery of fusions with their full-length isoform structure. However, due to higher sequencing error rates, fusion finding algorithms designed for short reads do not work. Here we present JAFFAL, to identify fusions from long-read transcriptome sequencing. We validate JAFFAL using simulations, cell lines, and patient data from Nanopore and PacBio. We apply JAFFAL to single-cell data and find fusions spanning three genes demonstrating transcripts detected from complex rearrangements. JAFFAL is available at https://github.com/Oshlack/JAFFA/wiki .
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Affiliation(s)
- Nadia M Davidson
- Peter MacCallum Cancer Centre, Victoria, Australia.
- School of BioSciences, University of Melbourne, Victoria, Australia.
- The Walter and Eliza Hall Institute, Victoria, Australia.
| | - Ying Chen
- Genome Institute of Singapore, Singapore, Singapore
| | - Teresa Sadras
- Peter MacCallum Cancer Centre, Victoria, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Victoria, Australia
| | - Georgina L Ryland
- Peter MacCallum Cancer Centre, Victoria, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Victoria, Australia
- Centre for Cancer Research, University of Melbourne, Victoria, Australia
| | - Piers Blombery
- Peter MacCallum Cancer Centre, Victoria, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Victoria, Australia
| | - Paul G Ekert
- Peter MacCallum Cancer Centre, Victoria, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Victoria, Australia
- Children's Cancer Institute, Lowy Cancer Centre, UNSW, Sydney, NSW, Australia
- School of Women's and Children's Health, UNSW, Sydney, NSW, Australia
- Murdoch Children's Research Institute, Victoria, Australia
| | - Jonathan Göke
- Genome Institute of Singapore, Singapore, Singapore
- National Cancer Centre Singapore, Singapore, Singapore
| | - Alicia Oshlack
- Peter MacCallum Cancer Centre, Victoria, Australia.
- School of BioSciences, University of Melbourne, Victoria, Australia.
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Victoria, Australia.
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21
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Evaluating a Targeted Cancer Therapy Approach Mediated by RNA trans-Splicing In Vitro and in a Xenograft Model for Epidermolysis Bullosa-Associated Skin Cancer. Int J Mol Sci 2022; 23:ijms23010575. [PMID: 35008999 PMCID: PMC8745581 DOI: 10.3390/ijms23010575] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 12/20/2021] [Accepted: 12/24/2021] [Indexed: 02/04/2023] Open
Abstract
Conventional anti-cancer therapies based on chemo- and/or radiotherapy represent highly effective means to kill cancer cells but lack tumor specificity and, therefore, result in a wide range of iatrogenic effects. A promising approach to overcome this obstacle is spliceosome-mediated RNA trans-splicing (SMaRT), which can be leveraged to target tumor cells while leaving normal cells unharmed. Notably, a previously established RNA trans-splicing molecule (RTM44) showed efficacy and specificity in exchanging the coding sequence of a cancer target gene (Ct-SLCO1B3) with the suicide gene HSV1-thymidine kinase in a colorectal cancer model, thereby rendering tumor cells sensitive to the prodrug ganciclovir (GCV). In the present work, we expand the application of this approach, using the same RTM44 in aggressive skin cancer arising in the rare genetic skin disease recessive dystrophic epidermolysis bullosa (RDEB). Stable expression of RTM44, but not a splicing-deficient control (NC), in RDEB-SCC cells resulted in expression of the expected fusion product at the mRNA and protein level. Importantly, systemic GCV treatment of mice bearing RTM44-expressing cancer cells resulted in a significant reduction in tumor volume and weight compared with controls. Thus, our results demonstrate the applicability of RTM44-mediated targeting of the cancer gene Ct-SLCO1B3 in a different malignancy.
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22
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Herrero-Hernandez P, Bergsma AJ, Pijnappel WWMP. Generation of Human iPSC-Derived Myotubes to Investigate RNA-Based Therapies In Vitro. Methods Mol Biol 2022; 2434:235-243. [PMID: 35213021 PMCID: PMC9703849 DOI: 10.1007/978-1-0716-2010-6_15] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Alternative pre-mRNA splicing can be cell-type specific and results in the generation of different protein isoforms from a single gene. Deregulation of canonical pre-mRNA splicing by disease-associated variants can result in genetic disorders. Antisense oligonucleotides (AONs) offer an attractive solution to modulate endogenous gene expression through alteration of pre-mRNA splicing events. Relevant in vitro models are crucial for appropriate evaluation of splicing modifying drugs. In this chapter, we describe how to investigate the splicing modulating activity of AONs in an in vitro skeletal muscle model, applied to Pompe disease. We also provide a detailed description of methods to visualize and analyze gene expression in differentiated skeletal muscle cells for the analysis of muscle differentiation and splicing outcome. The methodology described here is relevant to develop treatment options using AONs for other genetic muscle diseases as well, including Duchenne muscular dystrophy, myotonic dystrophy, and facioscapulohumeral muscular dystrophy.
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Affiliation(s)
- Pablo Herrero-Hernandez
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Pediatrics, Erasmus Medical Center, Rotterdam, The Netherlands
- Center for Lysosomal and Metabolic Diseases, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Atze J Bergsma
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Pediatrics, Erasmus Medical Center, Rotterdam, The Netherlands
- Center for Lysosomal and Metabolic Diseases, Erasmus Medical Center, Rotterdam, The Netherlands
| | - W W M Pim Pijnappel
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands.
- Department of Pediatrics, Erasmus Medical Center, Rotterdam, The Netherlands.
- Center for Lysosomal and Metabolic Diseases, Erasmus Medical Center, Rotterdam, The Netherlands.
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23
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Ustyantsev KV, Berezikov EV. Computational analysis of spliced leader trans-splicing in the regenerative flatworm Macrostomum lignano reveals its prevalence in conserved and stem cell related genes. Vavilovskii Zhurnal Genet Selektsii 2021; 25:101-107. [PMID: 34901707 PMCID: PMC8629364 DOI: 10.18699/vj21.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 12/03/2020] [Accepted: 12/08/2020] [Indexed: 11/28/2022] Open
Abstract
In eukaryotes, trans-splicing is a process of nuclear pre-mRNA maturation where two different RNA molecules are joined together by the spliceosomal machinery utilizing mechanisms similar to cis-splicing. In diverse taxa of
lower eukaryotes, spliced leader (SL) trans-splicing is the most frequent type of trans-splicing, when the same sequence
derived from short small nuclear RNA molecules, called SL RNAs, is attached to the 5’ ends of different non-processed
pre-mRNAs. One of the functions of SL trans-splicing is processing polycistronic pre-mRNA molecules transcribed from
operons, when several genes are transcribed as one pre-mRNA molecule. However, only a fraction of trans-spliced
genes reside in operons, suggesting that SL trans-splicing must also have some other, less understood functions. Regenerative flatworms are informative model organisms which hold the keys to understand the mechanism of stem
cell regulation and specialization during regeneration and homeostasis. Their ability to regenerate is fueled by the
division and differentiation of the adult somatic stem cell population called neoblasts. Macrostomum lignano is a flatworm model organism where substantial technological advances have been achieved in recent years, including the
development of transgenesis. Although a large fraction of genes in M. lignano were estimated to be SL trans-spliced,
SL trans-splicing was not studied in detail in M. lignano before. Here, we performed the first comprehensive study of
SL trans-splicing in M. lignano. By reanalyzing the existing genome and transcriptome data of M. lignano, we estimate
that 30 % of its genes are SL trans-spliced, 15 % are organized in operons, and almost 40 % are both SL trans-spliced
and in operons. We annotated and characterized the sequence of SL RNA and characterized conserved cis- and SL transsplicing motifs. Finally, we found that a majority of SL trans-spliced genes are evolutionarily conserved and significantly
over-represented in neoblast-specific genes. Our findings suggest an important role of SL trans-splicing in the regulation and maintenance of neoblasts in M. lignano.
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Affiliation(s)
- K V Ustyantsev
- Institute of Cytology and Genetics of Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - E V Berezikov
- Institute of Cytology and Genetics of Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
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24
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The Fusion of CLEC12A and MIR223HG Arises from a trans-Splicing Event in Normal and Transformed Human Cells. Int J Mol Sci 2021; 22:ijms222212178. [PMID: 34830054 PMCID: PMC8625150 DOI: 10.3390/ijms222212178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 10/30/2021] [Accepted: 11/03/2021] [Indexed: 11/17/2022] Open
Abstract
Chimeric RNAs are often associated with chromosomal rearrangements in cancer. In addition, they are also widely detected in normal tissues, contributing to transcriptomic complexity. Despite their prevalence, little is known about the characteristics and functions of chimeric RNAs. Here, we examine the genetic structure and biological roles of CLEC12A-MIR223HG, a novel chimeric transcript produced by the fusion of the cell surface receptor CLEC12A and the miRNA-223 host gene (MIR223HG), first identified in chronic myeloid leukemia (CML) patients. Surprisingly, we observed that CLEC12A-MIR223HG is not just expressed in CML, but also in a variety of normal tissues and cell lines. CLEC12A-MIR223HG expression is elevated in pro-monocytic cells resistant to chemotherapy and during monocyte-to-macrophage differentiation. We observed that CLEC12A-MIR223HG is a product of trans-splicing rather than a chromosomal rearrangement and that transcriptional activation of CLEC12A with the CRISPR/Cas9 Synergistic Activation Mediator (SAM) system increases CLEC12A-MIR223HG expression. CLEC12A-MIR223HG translates into a chimeric protein, which largely resembles CLEC12A but harbours an altered C-type lectin domain altering key disulphide bonds. These alterations result in differences in post-translational modifications, cellular localization, and protein-protein interactions. Taken together, our observations support a possible involvement of CLEC12A-MIR223HG in the regulation of CLEC12A function. Our workflow also serves as a template to study other uncharacterized chimeric RNAs.
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25
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Hu X, Li F, He J, Yang J, Jiang Y, Jiang M, Wei D, Chang L, Hejtmancik JF, Hou L, Ma X. LncRNA NEAT1 Recruits SFPQ to Regulate MITF Splicing and Control RPE Cell Proliferation. Invest Ophthalmol Vis Sci 2021; 62:18. [PMID: 34787639 PMCID: PMC8606808 DOI: 10.1167/iovs.62.14.18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Purpose Retinal pigment epithelium (RPE) cell proliferation is precisely regulated to maintain retinal homoeostasis. Microphthalmia-associated transcription factor (MITF), a critical transcription factor in RPE cells, has two alternatively spliced isoforms: (+)MITF and (-)MITF. Previous work has shown that (-)MITF but not (+)MITF inhibits RPE cell proliferation. This study aims to investigate the role of long non-coding RNA (lncRNA) nuclear-enriched abundant transcript 1 (NEAT1) in regulating MITF splicing and hence proliferation of RPE cells. Methods Mouse RPE, primary cultured mouse RPE cells, and different proliferative human embryonic stem cell (hESC)-RPE cells were used to evaluate the expression of (+)MITF, (-)MITF, and NEAT1 by reverse-transcription PCR (RT-PCR) or quantitative RT-PCR. NEAT1 was knocked down using specific small interfering RNAs (siRNAs). Splicing factor proline- and glutamine-rich (SFPQ) was overexpressed with the use of lentivirus infection. Cell proliferation was analyzed by cell number counting and Ki67 immunostaining. RNA immunoprecipitation (RIP) was used to analyze the co-binding between the SFPQ and MITF or NEAT1. Results NEAT1 was highly expressed in proliferative RPE cells, which had low expression of (-)MITF. Knockdown of NEAT1 in RPE cells switched the MITF splicing pattern to produce higher levels of (-)MITF and inhibited cell proliferation. Mechanistically, NEAT1 recruited SFPQ to bind directly with MITF mRNA to regulate its alternative splicing. Overexpression of SFPQ in ARPE-19 cells enhanced the binding enrichment of SFPQ to MITF and increased the splicing efficiency of (+)MITF. The binding affinity between SFPQ and MITF was decreased after NEAT1 knockdown. Conclusions NEAT1 acts as a scaffold to recruit SFPQ to MITF mRNA and promote its binding affinity, which plays an important role in regulating the alternative splicing of MITF and RPE cell proliferation.
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Affiliation(s)
- Xiaojuan Hu
- Laboratory of Developmental Cell Biology and Disease, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China.,State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou, China
| | - Fang Li
- Laboratory of Developmental Cell Biology and Disease, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China.,Department of Ophthalmology, The First Hospital of Wuhan, Wuhan, China
| | - Junhao He
- Laboratory of Developmental Cell Biology and Disease, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Juan Yang
- Laboratory of Developmental Cell Biology and Disease, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China.,State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou, China
| | - Ye Jiang
- Laboratory of Developmental Cell Biology and Disease, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Mingyuan Jiang
- Laboratory of Developmental Cell Biology and Disease, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Dandan Wei
- Laboratory of Developmental Cell Biology and Disease, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Lifu Chang
- Laboratory of Developmental Cell Biology and Disease, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - J Fielding Hejtmancik
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Ling Hou
- Laboratory of Developmental Cell Biology and Disease, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China.,State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou, China
| | - Xiaoyin Ma
- Laboratory of Developmental Cell Biology and Disease, School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China.,State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou, China
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26
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The role of nuclear organization in trans-splicing based expression of heat shock protein 90 in Giardia lamblia. PLoS Negl Trop Dis 2021; 15:e0009810. [PMID: 34559805 PMCID: PMC8494341 DOI: 10.1371/journal.pntd.0009810] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 10/06/2021] [Accepted: 09/13/2021] [Indexed: 11/19/2022] Open
Abstract
Hsp90 gene of G. lamblia has a split nature comprising two ORFs separated by 777 kb on chromosome 5. The ORFs of the split gene on chromosome 5 undergo transcription to generate independent pre-mRNAs that join by a unique trans-splicing reaction that remains partially understood. The canonical cis-acting nucleotide elements such as 5'SS-GU, 3'SS-AG, polypyrimidine tract and branch point adenine are present in the independent pre-mRNAs and therefore trans-splicing of Hsp90 must be assisted by spliceosomes in vivo. Using an approach of RNA-protein pull down, we show that an RNA helicase selectively interacts with HspN pre-mRNA. Our experiments involving high resolution chromosome conformation capture technology as well as DNA FISH show that the trans-spliced genes of Giardia are in three-dimensional spatial proximity in the nucleus. Altogether our study provides a glimpse into the in vivo mechanisms involving protein factors as well as chromatin structure to facilitate the unique inter-molecular post-transcriptional stitching of split genes in G. lamblia.
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27
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Mukherjee S, Detroja R, Balamurali D, Matveishina E, Medvedeva Y, Valencia A, Gorohovski A, Frenkel-Morgenstern M. Computational analysis of sense-antisense chimeric transcripts reveals their potential regulatory features and the landscape of expression in human cells. NAR Genom Bioinform 2021; 3:lqab074. [PMID: 34458728 PMCID: PMC8386243 DOI: 10.1093/nargab/lqab074] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 07/02/2021] [Accepted: 08/20/2021] [Indexed: 12/11/2022] Open
Abstract
Many human genes are transcribed from both strands and produce sense-antisense gene pairs. Sense-antisense (SAS) chimeric transcripts are produced upon the coalescing of exons/introns from both sense and antisense transcripts of the same gene. SAS chimera was first reported in prostate cancer cells. Subsequently, numerous SAS chimeras have been reported in the ChiTaRS-2.1 database. However, the landscape of their expression in human cells and functional aspects are still unknown. We found that longer palindromic sequences are a unique feature of SAS chimeras. Structural analysis indicates that a long hairpin-like structure formed by many consecutive Watson-Crick base pairs appears because of these long palindromic sequences, which possibly play a similar role as double-stranded RNA (dsRNA), interfering with gene expression. RNA-RNA interaction analysis suggested that SAS chimeras could significantly interact with their parental mRNAs, indicating their potential regulatory features. Here, 267 SAS chimeras were mapped in RNA-seq data from 16 healthy human tissues, revealing their expression in normal cells. Evolutionary analysis suggested the positive selection favoring sense-antisense fusions that significantly impacted the evolution of their function and structure. Overall, our study provides detailed insight into the expression landscape of SAS chimeras in human cells and identifies potential regulatory features.
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Affiliation(s)
- Sumit Mukherjee
- Cancer Genomics and BioComputing of Complex Diseases Lab, Azrieli Faculty of Medicine, Bar-Ilan University, Safed 1311502, Israel
| | - Rajesh Detroja
- Cancer Genomics and BioComputing of Complex Diseases Lab, Azrieli Faculty of Medicine, Bar-Ilan University, Safed 1311502, Israel
| | - Deepak Balamurali
- Cancer Genomics and BioComputing of Complex Diseases Lab, Azrieli Faculty of Medicine, Bar-Ilan University, Safed 1311502, Israel
| | - Elena Matveishina
- Department of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119234, Russian Federation
- Institute of Bioengineering, Research Centre of Biotechnology, Russian Academy of Sciences, Moscow 117312, Russian Federation
| | - Yulia A Medvedeva
- Institute of Bioengineering, Research Centre of Biotechnology, Russian Academy of Sciences, Moscow 117312, Russian Federation
- Department of Biomedical Physics, Moscow Institute of Technology, Dolgoprudny 141701, Russian Federation
| | - Alfonso Valencia
- Barcelona Supercomputing Center (BSC), C/ Jordi Girona 29, 08034, Barcelona, Spain
- ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
| | - Alessandro Gorohovski
- Cancer Genomics and BioComputing of Complex Diseases Lab, Azrieli Faculty of Medicine, Bar-Ilan University, Safed 1311502, Israel
| | - Milana Frenkel-Morgenstern
- Cancer Genomics and BioComputing of Complex Diseases Lab, Azrieli Faculty of Medicine, Bar-Ilan University, Safed 1311502, Israel
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28
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Hai Q, Smith JD. Acyl-Coenzyme A: Cholesterol Acyltransferase (ACAT) in Cholesterol Metabolism: From Its Discovery to Clinical Trials and the Genomics Era. Metabolites 2021; 11:metabo11080543. [PMID: 34436484 PMCID: PMC8398989 DOI: 10.3390/metabo11080543] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/10/2021] [Accepted: 08/12/2021] [Indexed: 11/16/2022] Open
Abstract
The purification and cloning of the acyl-coenzyme A: cholesterol acyltransferase (ACAT) enzymes and the sterol O-acyltransferase (SOAT) genes has opened new areas of interest in cholesterol metabolism given their profound effects on foam cell biology and intestinal lipid absorption. The generation of mouse models deficient in Soat1 or Soat2 confirmed the importance of their gene products on cholesterol esterification and lipoprotein physiology. Although these studies supported clinical trials which used non-selective ACAT inhibitors, these trials did not report benefits, and one showed an increased risk. Early genetic studies have implicated common variants in both genes with human traits, including lipoprotein levels, coronary artery disease, and Alzheimer’s disease; however, modern genome-wide association studies have not replicated these associations. In contrast, the common SOAT1 variants are most reproducibly associated with testosterone levels.
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29
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Zhang J, Hou L, Zuo Z, Ji P, Zhang X, Xue Y, Zhao F. Comprehensive profiling of circular RNAs with nanopore sequencing and CIRI-long. Nat Biotechnol 2021; 39:836-845. [PMID: 33707777 DOI: 10.1038/s41587-021-00842-6] [Citation(s) in RCA: 98] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 02/01/2021] [Accepted: 02/02/2021] [Indexed: 02/08/2023]
Abstract
Reconstructing the sequence of circular RNAs (circRNAs) from short RNA sequencing reads has proved challenging given the similarity of circRNAs and their corresponding linear messenger RNAs. Previous sequencing methods were unable to achieve high-throughput detection of full-length circRNAs. Here we describe a protocol for enrichment and full-length sequencing of circRNA isoforms using nanopore technology. Circular reverse transcription and size selection achieves a 20-fold higher enrichment of circRNAs from total RNA compared to previous methods. We developed an algorithm, called circRNA identifier using long-read sequencing data (CIRI-long), to reconstruct the sequence of circRNAs. The workflow was validated with simulated data and by comparison to Illumina sequencing as well as quantitative real-time RT-PCR. We used CIRI-long to analyze adult mouse brain samples and systematically profile circRNAs, including mitochondria-derived and transcriptional read-through circRNAs. We identified a new type of intronic self-ligated circRNA that exhibits special splicing and expression patterns. Our method takes advantage of nanopore long reads and enables unbiased reconstruction of full-length circRNA sequences.
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Affiliation(s)
- Jinyang Zhang
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Lingling Hou
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, China
| | - Zhenqiang Zuo
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, China
| | - Peifeng Ji
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, China
| | - Xiaorong Zhang
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Yuanchao Xue
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Fangqing Zhao
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, China. .,University of Chinese Academy of Sciences, Beijing, China. .,Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming, China. .,Key Laboratory of Systems Biology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Hangzhou, China.
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30
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Ou MY, Xiao Q, Ju XC, Zeng PM, Huang J, Sheng AL, Luo ZG. The CTNNBIP1-CLSTN1 fusion transcript regulates human neocortical development. Cell Rep 2021; 35:109290. [PMID: 34192541 DOI: 10.1016/j.celrep.2021.109290] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 02/17/2021] [Accepted: 06/02/2021] [Indexed: 12/21/2022] Open
Abstract
Fusion transcripts or RNAs have been found in both disordered and healthy human tissues and cells; however, their physiological functions in the brain development remain unknown. In the analysis of deposited RNA-sequence libraries covering early to middle embryonic stages, we identify 1,055 fusion transcripts present in the developing neocortex. Interestingly, 98 fusion transcripts exhibit distinct expression patterns in various neural progenitors (NPs) or neurons. We focus on CTNNBIP1-CLSTN1 (CTCL), which is enriched in outer radial glial cells that contribute to cortex expansion during human evolution. Intriguingly, downregulation of CTCL in cultured human cerebral organoids causes marked reduction in NPs and precocious neuronal differentiation, leading to impairment of organoid growth. Furthermore, the expression of CTCL fine-tunes Wnt/β-catenin signaling that controls cortex patterning. Together, this work provides evidence indicating important roles of fusion transcript in human brain development and evolution.
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Affiliation(s)
- Min-Yi Ou
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China; Institute of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qi Xiao
- Institute of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiang-Chun Ju
- Institute of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
| | - Peng-Ming Zeng
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Jing Huang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Ai-Li Sheng
- Institute of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Zhen-Ge Luo
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.
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31
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Murashko MM, Stasevich EM, Schwartz AM, Kuprash DV, Uvarova AN, Demin DE. The Role of RNA in DNA Breaks, Repair and Chromosomal Rearrangements. Biomolecules 2021; 11:biom11040550. [PMID: 33918762 PMCID: PMC8069526 DOI: 10.3390/biom11040550] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 03/31/2021] [Accepted: 04/07/2021] [Indexed: 12/28/2022] Open
Abstract
Incorrect reparation of DNA double-strand breaks (DSB) leading to chromosomal rearrangements is one of oncogenesis's primary causes. Recently published data elucidate the key role of various types of RNA in DSB formation, recognition and repair. With growing interest in RNA biology, increasing RNAs are classified as crucial at the different stages of the main pathways of DSB repair in eukaryotic cells: nonhomologous end joining (NHEJ) and homology-directed repair (HDR). Gene mutations or variation in expression levels of such RNAs can lead to local DNA repair defects, increasing the chromosome aberration frequency. Moreover, it was demonstrated that some RNAs could stimulate long-range chromosomal rearrangements. In this review, we discuss recent evidence demonstrating the role of various RNAs in DSB formation and repair. We also consider how RNA may mediate certain chromosomal rearrangements in a sequence-specific manner.
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Affiliation(s)
- Matvey Mikhailovich Murashko
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia; (M.M.M.); (E.M.S.); (A.M.S.); (D.V.K.); (A.N.U.)
| | - Ekaterina Mikhailovna Stasevich
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia; (M.M.M.); (E.M.S.); (A.M.S.); (D.V.K.); (A.N.U.)
| | - Anton Markovich Schwartz
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia; (M.M.M.); (E.M.S.); (A.M.S.); (D.V.K.); (A.N.U.)
- Moscow Institute of Physics and Technology, Department of Molecular and Biological Physics, 141701 Moscow, Russia
| | - Dmitriy Vladimirovich Kuprash
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia; (M.M.M.); (E.M.S.); (A.M.S.); (D.V.K.); (A.N.U.)
| | - Aksinya Nicolaevna Uvarova
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia; (M.M.M.); (E.M.S.); (A.M.S.); (D.V.K.); (A.N.U.)
| | - Denis Eriksonovich Demin
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia; (M.M.M.); (E.M.S.); (A.M.S.); (D.V.K.); (A.N.U.)
- Correspondence:
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32
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Guo W, Zhu A, Fan W, Adams RP, Mower JP. Extensive Shifts from Cis- to Trans-splicing of Gymnosperm Mitochondrial Introns. Mol Biol Evol 2021; 37:1615-1620. [PMID: 32027368 DOI: 10.1093/molbev/msaa029] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Hundreds of plant mitogenomes have been sequenced from angiosperms, but relatively few mitogenomes are available from its sister lineage, gymnosperms. To examine mitogenomic diversity among extant gymnosperms, we generated draft mitogenomes from 11 diverse species and compared them with four previously published mitogenomes. Examined mitogenomes from Pinaceae and cycads retained all 41 protein genes and 26 introns present in the common ancestor of seed plants, whereas gnetophyte and cupressophyte mitogenomes experienced extensive gene and intron loss. In Pinaceae and cupressophyte mitogenomes, an unprecedented number of exons are distantly dispersed, requiring trans-splicing of 50-70% of mitochondrial introns to generate mature transcripts. RNAseq data confirm trans-splicing of these dispersed exons in Pinus. The prevalence of trans-splicing in vascular plant lineages with recombinogenic mitogenomes suggests that genomic rearrangement is the primary cause of shifts from cis- to trans-splicing in plant mitochondria.
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Affiliation(s)
- Wenhu Guo
- Center for Plant Science Innovation, University of Nebraska, Lincoln, NE.,School of Biological Sciences, University of Nebraska, Lincoln, NE
| | - Andan Zhu
- Center for Plant Science Innovation, University of Nebraska, Lincoln, NE.,Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE.,Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Weishu Fan
- Center for Plant Science Innovation, University of Nebraska, Lincoln, NE.,Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE.,Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China
| | | | - Jeffrey P Mower
- Center for Plant Science Innovation, University of Nebraska, Lincoln, NE.,Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE
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Borbolis F, Syntichaki P. Biological implications of decapping: beyond bulk mRNA decay. FEBS J 2021; 289:1457-1475. [PMID: 33660392 DOI: 10.1111/febs.15798] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 02/21/2021] [Accepted: 03/07/2021] [Indexed: 12/12/2022]
Abstract
It is well established that mRNA steady-state levels do not directly correlate with transcription rate. This is attributed to the multiple post-transcriptional mechanisms, which control both mRNA turnover and translation within eukaryotic cells. One such mechanism is the removal of the 5' end cap structure of RNAs (decapping). This 5' cap plays a fundamental role in cellular functions related to mRNA processing, transport, translation, quality control, and decay, while its chemical modifications influence the fate of cytoplasmic mRNAs. Decapping is a highly controlled process, performed by multiple decapping enzymes, and regulated by complex cellular networks. In this review, we provide an updated synopsis of 5' end modifications and functions, and give an overview of mRNA decapping enzymes, presenting their enzymatic properties. Focusing on DCP2 decapping enzyme, a major component on the 5'-3' mRNA decay pathway, we describe cis-elements and trans-acting factors that affect its activity, substrate specificity, and cellular localization. Finally, we discuss current knowledge on the biological functions of mRNA decapping and decay factors, highlighting the major questions that remain to be addressed.
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Affiliation(s)
- Fivos Borbolis
- Biomedical Research Foundation of the Academy of Athens, Center of Basic Research, Athens, Greece
| | - Popi Syntichaki
- Biomedical Research Foundation of the Academy of Athens, Center of Basic Research, Athens, Greece
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34
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Taniue K, Akimitsu N. Fusion Genes and RNAs in Cancer Development. Noncoding RNA 2021; 7:10. [PMID: 33557176 PMCID: PMC7931065 DOI: 10.3390/ncrna7010010] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/02/2021] [Accepted: 02/03/2021] [Indexed: 02/07/2023] Open
Abstract
Fusion RNAs are a hallmark of some cancers. They result either from chromosomal rearrangements or from splicing mechanisms that are non-chromosomal rearrangements. Chromosomal rearrangements that result in gene fusions are particularly prevalent in sarcomas and hematopoietic malignancies; they are also common in solid tumors. The splicing process can also give rise to more complex RNA patterns in cells. Gene fusions frequently affect tyrosine kinases, chromatin regulators, or transcription factors, and can cause constitutive activation, enhancement of downstream signaling, and tumor development, as major drivers of oncogenesis. In addition, some fusion RNAs have been shown to function as noncoding RNAs and to affect cancer progression. Fusion genes and RNAs will therefore become increasingly important as diagnostic and therapeutic targets for cancer development. Here, we discuss the function, biogenesis, detection, clinical relevance, and therapeutic implications of oncogenic fusion genes and RNAs in cancer development. Further understanding the molecular mechanisms that regulate how fusion RNAs form in cancers is critical to the development of therapeutic strategies against tumorigenesis.
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Affiliation(s)
- Kenzui Taniue
- Isotope Science Center, The University of Tokyo, 2-11-16, Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
- Cancer Genomics and Precision Medicine, Division of Gastroenterology and Hematology/Oncology, Department of Medicine, Asahikawa Medical University, 2-1 Midorigaoka Higashi, Asahikawa, Hokkaido 078-8510, Japan
| | - Nobuyoshi Akimitsu
- Isotope Science Center, The University of Tokyo, 2-11-16, Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
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35
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Splicing mutations in inherited retinal diseases. Prog Retin Eye Res 2021. [DOI: 10.1016/j.preteyeres.2020.100874
expr 921883647 + 833887994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
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36
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Chen W, Cui W, Qiu Y, Cui D. Research Progress of Chimeric RNA and Health. Health (London) 2021. [DOI: 10.4236/health.2021.134036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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37
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Abstract
BACKGROUND RNA trans-splicing joins exons from different pre-mRNA transcripts to generate a chimeric product. Trans-splicing can also occur at the protein level, with split inteins mediating the ligation of separate gene products to generate a mature protein. SOURCES OF DATA Comprehensive literature search of published research papers and reviews using Pubmed. AREAS OF AGREEMENT Trans-splicing techniques have been used to target a wide range of diseases in both in vitro and in vivo models, resulting in RNA, protein and functional correction. AREAS OF CONTROVERSY Off-target effects can lead to therapeutically undesirable consequences. In vivo efficacy is typically low, and delivery issues remain a challenge. GROWING POINTS Trans-splicing provides a promising avenue for developing novel therapeutic approaches. However, much more research needs to be done before developing towards preclinical studies. AREAS TIMELY FOR DEVELOPING RESEARCH Increasing trans-splicing efficacy and specificity by rational design, screening and competitive inhibition of endogenous cis-splicing.
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Affiliation(s)
- Elizabeth M Hong
- Department of Medicine, University of Cambridge, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 2QQ, UK
| | - Carin K Ingemarsdotter
- Department of Medicine, University of Cambridge, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 2QQ, UK
| | - Andrew M L Lever
- Department of Medicine, University of Cambridge, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 2QQ, UK
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Gumińska N, Zakryś B, Milanowski R. A New Type of Circular RNA derived from Nonconventional Introns in Nuclear Genes of Euglenids. J Mol Biol 2020; 433:166758. [PMID: 33316270 DOI: 10.1016/j.jmb.2020.166758] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 12/06/2020] [Accepted: 12/07/2020] [Indexed: 10/22/2022]
Abstract
Nuclear protein-coding genes of euglenids (Discoba, Euglenozoa, Euglenida) contain conventional (spliceosomal) and nonconventional introns. The latter have been found only in euglenozoans. A unique feature of nonconventional introns is the ability to form a stable and slightly conserved RNA secondary structure bringing together intron ends and placing adjacent exons in proximity. To date, little is known about the mechanism of their excision (e.g. whether it involves the spliceosome or not). The tubA gene of Euglena gracilis harbors three conventional and three nonconventional introns. While the conventional introns are excised as lariats, nonconventional introns are present in the cell solely as circular RNAs with full-length ends. Based on this discovery as well as on previous observations indicating that nonconventional introns are observed frequently at unique positions of genes, we suggest that this new type of intronic circRNA might play a role in intron mobility.
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Affiliation(s)
- Natalia Gumińska
- Institute of Evolutionary Biology, Faculty of Biology, Biological and Chemical Research Center, University of Warsaw, ul. Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Bożena Zakryś
- Institute of Evolutionary Biology, Faculty of Biology, Biological and Chemical Research Center, University of Warsaw, ul. Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Rafał Milanowski
- Institute of Evolutionary Biology, Faculty of Biology, Biological and Chemical Research Center, University of Warsaw, ul. Żwirki i Wigury 101, 02-089 Warsaw, Poland.
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39
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Xu B, Meng Y, Jin Y. RNA structures in alternative splicing and back-splicing. WILEY INTERDISCIPLINARY REVIEWS-RNA 2020; 12:e1626. [PMID: 32929887 DOI: 10.1002/wrna.1626] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 08/14/2020] [Accepted: 08/22/2020] [Indexed: 12/12/2022]
Abstract
Alternative splicing greatly expands the transcriptomic and proteomic diversities related to physiological and developmental processes in higher eukaryotes. Splicing of long noncoding RNAs, and back- and trans- splicing further expanded the regulatory repertoire of alternative splicing. RNA structures were shown to play an important role in regulating alternative splicing and back-splicing. Application of novel sequencing technologies made it possible to identify genome-wide RNA structures and interaction networks, which might provide new insights into RNA splicing regulation in vitro to in vivo. The emerging transcription-folding-splicing paradigm is changing our understanding of RNA alternative splicing regulation. Here, we review the insights into the roles and mechanisms of RNA structures in alternative splicing and back-splicing, as well as how disruption of these structures affects alternative splicing and then leads to human diseases. This article is categorized under: RNA Processing > Splicing Regulation/Alternative Splicing RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems.
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Affiliation(s)
- Bingbing Xu
- MOE Laboratory of Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, College of Life Sciences, Zhejiang University, Zhejiang, Hangzhou, China
| | - Yijun Meng
- College of Life and Environmental Sciences, Hangzhou Normal University, Zhejiang, Hangzhou, China
| | - Yongfeng Jin
- MOE Laboratory of Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, College of Life Sciences, Zhejiang University, Zhejiang, Hangzhou, China
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40
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Calvelo J, Juan H, Musto H, Koziol U, Iriarte A. SLFinder, a pipeline for the novel identification of splice-leader sequences: a good enough solution for a complex problem. BMC Bioinformatics 2020; 21:293. [PMID: 32640978 PMCID: PMC7346339 DOI: 10.1186/s12859-020-03610-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 06/17/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Spliced Leader trans-splicing is an important mechanism for the maturation of mRNAs in several lineages of eukaryotes, including several groups of parasites of great medical and economic importance. Nevertheless, its study across the tree of life is severely hindered by the problem of identifying the SL sequences that are being trans-spliced. RESULTS In this paper we present SLFinder, a four-step pipeline meant to identify de novo candidate SL sequences making very few assumptions regarding the SL sequence properties. The pipeline takes transcriptomic de novo assemblies and a reference genome as input and allows the user intervention on several points to account for unexpected features of the dataset. The strategy and its implementation were tested on real RNAseq data from species with and without SL Trans-Splicing. CONCLUSIONS SLFinder is capable to identify SL candidates with good precision in a reasonable amount of time. It is especially suitable for species with unknown SL sequences, generating candidate sequences for further refining and experimental validation.
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Affiliation(s)
- Javier Calvelo
- Laboratorio de Biología Computacional, Departamento de Desarrollo Biotecnológico, Instituto de Higiene, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
- Unidad de Genómica Evolutiva, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
- Sección Biología Celular, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Hernán Juan
- Laboratorio de Biología Computacional, Departamento de Desarrollo Biotecnológico, Instituto de Higiene, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Héctor Musto
- Unidad de Genómica Evolutiva, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Uriel Koziol
- Sección Biología Celular, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Andrés Iriarte
- Laboratorio de Biología Computacional, Departamento de Desarrollo Biotecnológico, Instituto de Higiene, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay.
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41
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Splicing mutations in inherited retinal diseases. Prog Retin Eye Res 2020; 80:100874. [PMID: 32553897 DOI: 10.1016/j.preteyeres.2020.100874] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 05/30/2020] [Accepted: 05/31/2020] [Indexed: 12/15/2022]
Abstract
Mutations which induce aberrant transcript splicing represent a distinct class of disease-causing genetic variants in retinal disease genes. Such mutations may either weaken or erase regular splice sites or create novel splice sites which alter exon recognition. While mutations affecting the canonical GU-AG dinucleotides at the splice donor and splice acceptor site are highly predictive to cause a splicing defect, other variants in the vicinity of the canonical splice sites or those affecting additional cis-acting regulatory sequences within exons or introns are much more difficult to assess or even to recognize and require additional experimental validation. Splicing mutations are unique in that the actual outcome for the transcript (e.g. exon skipping, pseudoexon inclusion, intron retention) and the encoded protein can be quite different depending on the individual mutation. In this article, we present an overview on the current knowledge about and impact of splicing mutations in inherited retinal diseases. We introduce the most common sub-classes of splicing mutations including examples from our own work and others and discuss current strategies for the identification and validation of splicing mutations, as well as therapeutic approaches, open questions, and future perspectives in this field of research.
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Abstract
Chimeric RNAs are hybrid transcripts containing exons from two separate genes. Chimeric RNAs are traditionally considered to be transcribed from fusion genes caused by chromosomal rearrangement. These canonical chimeric RNAs are well characterized to be expressed in a cancer-unique pattern and/or act as oncogene products. However, benefited by the development of advanced deep sequencing technologies, novel types of non-canonical chimeric RNAs have been discovered to be generated from intergenic splicing without genomic aberrations. They can be formed through trans-splicing or cis-splicing between adjacent genes (cis-SAGe) mechanisms. Non-canonical chimeric RNAs are widely detected in normal physiology, although several have been shown to have a cancer-specific expression pattern. Further studies have indicated that some of them play fundamental roles in controlling cell growth and motility, and may have functions independent of the parental genes. These discoveries are unveiling a new layer of the functional transcriptome and are also raising the possibility of utilizing non-canonical chimeric RNAs as cancer diagnostic markers and therapeutic targets. In this chapter, we will overview different categories of chimeric RNAs and their expression in various types of cancerous and normal samples. Acknowledging that chimeric RNAs are not unique to cancer, we will discuss both bioinformatic and biological methods to identify credible cancer-specific chimeric RNAs. Furthermore, we will describe downstream methods to explore their molecular processing mechanisms and potential functions. A better understanding of the biogenesis mechanisms and functional products of cancer-specific chimeric RNAs will pave ways for the development of novel cancer biomarkers and therapeutic targets.
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Affiliation(s)
- Xinrui Shi
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Virginia, Charlottesville, VA, United States
| | - Sandeep Singh
- Department of Pathology, School of Medicine, University of Virginia, Charlottesville, VA, United States
| | - Emily Lin
- Department of Pathology, School of Medicine, University of Virginia, Charlottesville, VA, United States
| | - Hui Li
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Virginia, Charlottesville, VA, United States; Department of Pathology, School of Medicine, University of Virginia, Charlottesville, VA, United States.
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43
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Heyer EE, Blackburn J. Sequencing Strategies for Fusion Gene Detection. Bioessays 2020; 42:e2000016. [DOI: 10.1002/bies.202000016] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 03/11/2020] [Indexed: 02/06/2023]
Affiliation(s)
- Erin E. Heyer
- The Kinghorn Cancer CentreGarvan Institute of Medical Research 384 Victoria Street Darlinghurst NSW 2010 Australia
| | - James Blackburn
- The Kinghorn Cancer CentreGarvan Institute of Medical Research 384 Victoria Street Darlinghurst NSW 2010 Australia
- Faculty of Medicine, St. Vincent's Clinical SchoolUNSW, St Vincent's Hospital Victoria Street Darlinghurst NSW 2010 Australia
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44
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Liu C, Zhang Y, Li X, Jia Y, Li F, Li J, Zhang Z. Evidence of constraint in the 3D genome for trans-splicing in human cells. SCIENCE CHINA-LIFE SCIENCES 2020; 63:1380-1393. [PMID: 32221814 DOI: 10.1007/s11427-019-1609-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 12/04/2019] [Indexed: 10/24/2022]
Abstract
Fusion transcripts are commonly found in eukaryotes, and many aberrant fusions are associated with severe diseases, including cancer. One class of fusion transcripts is generated by joining separate transcripts through trans-splicing. However, the mechanism of trans-splicing in mammals remains largely elusive. Here we showed evidence to support an intuitive hypothesis that attributes trans-sphcing to the spatial proximity between premature transcripts. A novel trans-splicing detection tool (TSD) was developed to reliably identify intra-chromosomal trans-splicing events (iTSEs) from RNA-seq data. TSD can maintain a remarkable balance between sensitivity and accuracy, thus distinguishing it from most state-of-the-art tools. The accuracy of TSD was experimentally demonstrated by excluding potential false discovery from mosaic genome or template switching during PCR. We showed that iTSEs identified by TSD were frequently found between genomic regulatory elements, which are known to be more prone to interact with each other. Moreover, iTSE sites may be more physically adjacent to each other than random control in the tested human lymphoblastoid cell line according to Hi-C data. Our results suggest that trans-splicing and 3D genome architecture may be coupled in mammals and that our pipeline, TSD, may facilitate investigations of trans-splicing on a systematic and accurate level previously thought impossible.
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Affiliation(s)
- Cong Liu
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, and China National Center for Bioinformation, Chinese Academy of Sciences, Beijing, 100101, China.,School of Life Science, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yiqun Zhang
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, and China National Center for Bioinformation, Chinese Academy of Sciences, Beijing, 100101, China.,School of Life Science, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiaoli Li
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, and China National Center for Bioinformation, Chinese Academy of Sciences, Beijing, 100101, China.,School of Life Science, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yan Jia
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, and China National Center for Bioinformation, Chinese Academy of Sciences, Beijing, 100101, China
| | - Feifei Li
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, and China National Center for Bioinformation, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Jing Li
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, and China National Center for Bioinformation, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Zhihua Zhang
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, and China National Center for Bioinformation, Chinese Academy of Sciences, Beijing, 100101, China. .,School of Life Science, University of Chinese Academy of Sciences, Beijing, 100049, China.
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45
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Vellichirammal NN, Albahrani A, Banwait JK, Mishra NK, Li Y, Roychoudhury S, Kling MJ, Mirza S, Bhakat KK, Band V, Joshi SS, Guda C. Pan-Cancer Analysis Reveals the Diverse Landscape of Novel Sense and Antisense Fusion Transcripts. MOLECULAR THERAPY. NUCLEIC ACIDS 2020; 19:1379-1398. [PMID: 32160708 PMCID: PMC7044684 DOI: 10.1016/j.omtn.2020.01.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 01/03/2020] [Accepted: 01/14/2020] [Indexed: 01/26/2023]
Abstract
Gene fusions that contribute to oncogenicity can be explored for identifying cancer biomarkers and potential drug targets. To investigate the nature and distribution of fusion transcripts in cancer, we examined the transcriptome data of about 9,000 primary tumors from 33 different cancers in TCGA (The Cancer Genome Atlas) along with cell line data from CCLE (Cancer Cell Line Encyclopedia) using ChimeRScope, a novel fusion detection algorithm. We identified several fusions with sense (canonical, 39%) or antisense (non-canonical, 61%) transcripts recurrent across cancers. The majority of the recurrent non-canonical fusions found in our study are novel, unexplored, and exhibited highly variable profiles across cancers, with breast cancer and glioblastoma having the highest and lowest rates, respectively. Overall, 4,344 recurrent fusions were identified from TCGA in this study, of which 70% were novel. Additional analysis of 802 tumor-derived cell line transcriptome data across 20 cancers revealed significant variability in recurrent fusion profiles between primary tumors and corresponding cell lines. A subset of canonical and non-canonical fusions was validated by examining the structural variation evidence in whole-genome sequencing (WGS) data or by Sanger sequencing of fusion junctions. Several recurrent fusion genes identified in our study show promise for drug repurposing in basket trials and present opportunities for mechanistic studies.
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Affiliation(s)
| | - Abrar Albahrani
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Jasjit K Banwait
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA; Bioinformatics and Systems Biology Core. University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Nitish K Mishra
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - You Li
- HitGen, South Keyuan Road 88, Chengdu, China
| | - Shrabasti Roychoudhury
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Mathew J Kling
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Sameer Mirza
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Kishor K Bhakat
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Vimla Band
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Shantaram S Joshi
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Chittibabu Guda
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA; Bioinformatics and Systems Biology Core. University of Nebraska Medical Center, Omaha, NE 68198, USA.
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46
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LaRoche-Johnston F, Monat C, Cousineau B. Detection of Group II Intron-Generated Chimeric mRNAs in Bacterial Cells. Methods Mol Biol 2020; 2079:95-107. [PMID: 31728964 DOI: 10.1007/978-1-4939-9904-0_7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Chimeric RNAs are the transcripts composed of exons from two separate genes or transcripts. Although the presence of these joined RNA molecules have mainly been documented in a variety of eukaryotes, we recently demonstrated that the Ll.LtrB group II intron, from the gram-positive bacterium Lactococcus lactis, can generate chimeric mRNAs through a novel intergenic trans-splicing pathway. Here we describe the detailed experimental procedures to detect group II intron-generated mRNA-mRNA chimeras from total RNA extracts using stringent reverse transcription conditions along with a reverse splicing-deficient group II intron as a negative control.
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Affiliation(s)
| | - Caroline Monat
- Department of Microbiology and Immunology, McGill University, Montréal, QC, Canada
| | - Benoit Cousineau
- Department of Microbiology and Immunology, McGill University, Montréal, QC, Canada.
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47
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Hu DG, Hulin JUA, Nair PC, Haines AZ, McKinnon RA, Mackenzie PI, Meech R. The UGTome: The expanding diversity of UDP glycosyltransferases and its impact on small molecule metabolism. Pharmacol Ther 2019; 204:107414. [PMID: 31647974 DOI: 10.1016/j.pharmthera.2019.107414] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 09/17/2019] [Indexed: 01/23/2023]
Abstract
The UDP glycosyltransferase (UGT) superfamily of enzymes is responsible for the metabolism and clearance of thousands of lipophilic chemicals including drugs, toxins and endogenous signaling molecules. They provide a protective interface between the organism and its chemical-rich environment, as well as controlling critical signaling pathways to maintain healthy tissue function. UGTs are associated with drug responses and interactions, as well as a wide range of diseases including cancer. The human genome contains 22 UGT genes; however as befitting their exceptionally diverse substrate ranges and biological activities, the output of these UGT genes is functionally diversified by multiple processes including alternative splicing, post-translational modification, homo- and hetero-oligomerization, and interactions with other proteins. All UGT genes are subject to extensive alternative splicing generating variant/truncated UGT proteins with altered functions including the capacity to dominantly modulate/inhibit cognate full-length forms. Heterotypic oligomerization of different UGTs can alter kinetic properties relative to monotypic complexes, and potentially produce novel substrate specificities. Moreover, the recently profiled interactions of UGTs with non-UGT proteins may facilitate coordination between different metabolic processes, as well as providing opportunities for UGTs to engage in novel 'moonlighting' functions. Herein we provide a detailed and comprehensive review of all known modes of UGT functional diversification and propose a UGTome model to describe the resulting expansion of metabolic capacity and its potential to modulate drug/xenobiotic responses and cell behaviours in normal and disease contexts.
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Affiliation(s)
- Dong Gui Hu
- Department of Clinical Pharmacology and Flinders Cancer Centre, Flinders University College of Medicine and Public Health, Flinders Medical Centre, Bedford Park, South Australia, Australia
| | - J Ulie-Ann Hulin
- Department of Clinical Pharmacology and Flinders Cancer Centre, Flinders University College of Medicine and Public Health, Flinders Medical Centre, Bedford Park, South Australia, Australia
| | - Pramod C Nair
- Department of Clinical Pharmacology and Flinders Cancer Centre, Flinders University College of Medicine and Public Health, Flinders Medical Centre, Bedford Park, South Australia, Australia
| | - Alex Z Haines
- Department of Clinical Pharmacology and Flinders Cancer Centre, Flinders University College of Medicine and Public Health, Flinders Medical Centre, Bedford Park, South Australia, Australia
| | - Ross A McKinnon
- Department of Clinical Pharmacology and Flinders Cancer Centre, Flinders University College of Medicine and Public Health, Flinders Medical Centre, Bedford Park, South Australia, Australia
| | - Peter I Mackenzie
- Department of Clinical Pharmacology and Flinders Cancer Centre, Flinders University College of Medicine and Public Health, Flinders Medical Centre, Bedford Park, South Australia, Australia
| | - Robyn Meech
- Department of Clinical Pharmacology and Flinders Cancer Centre, Flinders University College of Medicine and Public Health, Flinders Medical Centre, Bedford Park, South Australia, Australia.
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48
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Vázquez-Domínguez I, Garanto A, Collin RWJ. Molecular Therapies for Inherited Retinal Diseases-Current Standing, Opportunities and Challenges. Genes (Basel) 2019; 10:genes10090654. [PMID: 31466352 PMCID: PMC6770110 DOI: 10.3390/genes10090654] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 08/23/2019] [Accepted: 08/26/2019] [Indexed: 12/15/2022] Open
Abstract
Inherited retinal diseases (IRDs) are both genetically and clinically highly heterogeneous and have long been considered incurable. Following the successful development of a gene augmentation therapy for biallelic RPE65-associated IRD, this view has changed. As a result, many different therapeutic approaches are currently being developed, in particular a large variety of molecular therapies. These are depending on the severity of the retinal degeneration, knowledge of the pathophysiological mechanism underlying each subtype of IRD, and the therapeutic target molecule. DNA therapies include approaches such as gene augmentation therapy, genome editing and optogenetics. For some genetic subtypes of IRD, RNA therapies and compound therapies have also shown considerable therapeutic potential. In this review, we summarize the current state-of-the-art of various therapeutic approaches, including the pros and cons of each strategy, and outline the future challenges that lie ahead in the combat against IRDs.
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Affiliation(s)
- Irene Vázquez-Domínguez
- Department of Human Genetics and Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525GA Nijmegen, The Netherlands
| | - Alejandro Garanto
- Department of Human Genetics and Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525GA Nijmegen, The Netherlands.
| | - Rob W J Collin
- Department of Human Genetics and Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6525GA Nijmegen, The Netherlands.
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49
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Chuang TJ, Chen YJ, Chen CY, Mai TL, Wang YD, Yeh CS, Yang MY, Hsiao YT, Chang TH, Kuo TC, Cho HH, Shen CN, Kuo HC, Lu MY, Chen YH, Hsieh SC, Chiang TW. Integrative transcriptome sequencing reveals extensive alternative trans-splicing and cis-backsplicing in human cells. Nucleic Acids Res 2019; 46:3671-3691. [PMID: 29385530 PMCID: PMC6283421 DOI: 10.1093/nar/gky032] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 01/13/2018] [Indexed: 01/16/2023] Open
Abstract
Transcriptionally non-co-linear (NCL) transcripts can originate from trans-splicing (trans-spliced RNA; 'tsRNA') or cis-backsplicing (circular RNA; 'circRNA'). While numerous circRNAs have been detected in various species, tsRNAs remain largely uninvestigated. Here, we utilize integrative transcriptome sequencing of poly(A)- and non-poly(A)-selected RNA-seq data from diverse human cell lines to distinguish between tsRNAs and circRNAs. We identified 24,498 NCL events and found that a considerable proportion (20-35%) of them arise from both tsRNAs and circRNAs, representing extensive alternative trans-splicing and cis-backsplicing in human cells. We show that sequence generalities of exon circularization are also observed in tsRNAs. Recapitulation of NCL RNAs further shows that inverted Alu repeats can simultaneously promote the formation of tsRNAs and circRNAs. However, tsRNAs and circRNAs exhibit quite different, or even opposite, expression patterns, in terms of correlation with the expression of their co-linear counterparts, expression breadth/abundance, transcript stability, and subcellular localization preference. These results indicate that tsRNAs and circRNAs may play different regulatory roles and analysis of NCL events should take the joint effects of different NCL-splicing types and joint effects of multiple NCL events into consideration. This study describes the first transcriptome-wide analysis of trans-splicing and cis-backsplicing, expanding our understanding of the complexity of the human transcriptome.
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Affiliation(s)
- Trees-Juen Chuang
- Genomics Research Center, Academia Sinica, Taipei 11529, Taiwan.,Genome and Systems Biology Degree Program, National Taiwan University, Taipei 10617 & Academia Sinica, Taipei 11529, Taiwan
| | - Yen-Ju Chen
- Genomics Research Center, Academia Sinica, Taipei 11529, Taiwan.,Genome and Systems Biology Degree Program, National Taiwan University, Taipei 10617 & Academia Sinica, Taipei 11529, Taiwan
| | - Chia-Ying Chen
- Genomics Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Te-Lun Mai
- Genomics Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Yi-Da Wang
- Genomics Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Chung-Shu Yeh
- Genomics Research Center, Academia Sinica, Taipei 11529, Taiwan.,Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei 11221, Taiwan
| | - Min-Yu Yang
- Genomics Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Yu-Ting Hsiao
- Genomics Research Center, Academia Sinica, Taipei 11529, Taiwan
| | | | - Tzu-Chien Kuo
- Genomics Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Hsin-Hua Cho
- Genomics Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Chia-Ning Shen
- Genomics Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Hung-Chih Kuo
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Mei-Yeh Lu
- High Throughput Genomics Core, Biodiversity Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Yi-Hua Chen
- High Throughput Genomics Core, Biodiversity Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Shan-Chi Hsieh
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Tai-Wei Chiang
- Genomics Research Center, Academia Sinica, Taipei 11529, Taiwan
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50
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Tikhonov M, Utkina M, Maksimenko O, Georgiev P. Conserved sequences in the Drosophila mod(mdg4) intron promote poly(A)-independent transcription termination and trans-splicing. Nucleic Acids Res 2019; 46:10608-10618. [PMID: 30102331 PMCID: PMC6237743 DOI: 10.1093/nar/gky716] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 07/26/2018] [Indexed: 11/15/2022] Open
Abstract
Alternative splicing (AS) is a regulatory mechanism of gene expression that greatly expands the coding capacities of genomes by allowing the generation of multiple mRNAs from a single gene. In Drosophila, the mod(mdg4) locus is an extreme example of AS that produces more than 30 different mRNAs via trans-splicing that joins together the common exons and the 3′ variable exons generated from alternative promoters. To map the regions required for trans-splicing, we have developed an assay for measuring trans-splicing events and identified a 73-bp region in the last common intron that is critical for trans-splicing of three pre-mRNAs synthesized from different DNA strands. We have also found that conserved sequences in the distal part of the last common intron induce polyadenylation-independent transcription termination and are enriched by paused RNA polymerase II (RNAP II). These results suggest that all mod(mdg4) mRNAs are formed by joining in trans the 5′ splice site in the last common exon with the 3′ splice site in one of the alternative exons.
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Affiliation(s)
- Maxim Tikhonov
- Department of the Control of Genetic Processes, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., Moscow 119334, Russia
| | - Marina Utkina
- Department of the Control of Genetic Processes, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., Moscow 119334, Russia
| | - Oksana Maksimenko
- Group of Molecular Organization of Genome, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., Moscow 119334, Russia
| | - Pavel Georgiev
- Department of the Control of Genetic Processes, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., Moscow 119334, Russia
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