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Rivera M, Ayon OS, Diaconescu-Grabari S, Pottel J, Moitessier N, Mittermaier A, McKeague M. A sensitive and scalable fluorescence anisotropy single stranded RNA targeting approach for monitoring riboswitch conformational states. Nucleic Acids Res 2024; 52:3164-3179. [PMID: 38375901 PMCID: PMC11014391 DOI: 10.1093/nar/gkae118] [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: 09/19/2023] [Revised: 02/02/2024] [Accepted: 02/07/2024] [Indexed: 02/21/2024] Open
Abstract
The capacity of riboswitches to undergo conformational changes in response to binding their native ligands is closely tied to their functional roles and is an attractive target for antimicrobial drug design. Here, we established a probe-based fluorescence anisotropy assay to monitor riboswitch conformational switching with high sensitivity and throughput. Using the Bacillus subtillis yitJ S-Box (SAM-I), Fusobacterium nucleatum impX RFN element of (FMN) and class-I cyclic-di-GMP from Vibrio cholerae riboswitches as model systems, we developed short fluorescent DNA probes that specifically recognize either ligand-free or -bound riboswitch conformational states. We showed that increasing concentrations of native ligands cause measurable and reproducible changes in fluorescence anisotropy that correlate with riboswitch conformational changes observed by native gel analysis. Furthermore, we applied our assay to several ligand analogues and confirmed that it can discriminate between ligands that bind, triggering the native conformational change, from those that bind without causing the conformational change. This new platform opens the possibility of high-throughput screening compound libraries to identify potential new antibiotics that specifically target functional conformational changes in riboswitches.
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Affiliation(s)
- Maira Rivera
- Department of Chemistry, Faculty of Science, McGill University, Montreal, QC H3A 0B8, Canada
| | - Omma S Ayon
- Department of Chemistry, Faculty of Science, McGill University, Montreal, QC H3A 0B8, Canada
| | | | - Joshua Pottel
- Molecular Forecaster Inc. 910-2075 Robert Bourassa, Montreal, QC H3A 2L1, Canada
| | - Nicolas Moitessier
- Department of Chemistry, Faculty of Science, McGill University, Montreal, QC H3A 0B8, Canada
- Molecular Forecaster Inc. 910-2075 Robert Bourassa, Montreal, QC H3A 2L1, Canada
| | - Anthony Mittermaier
- Department of Chemistry, Faculty of Science, McGill University, Montreal, QC H3A 0B8, Canada
| | - Maureen McKeague
- Department of Chemistry, Faculty of Science, McGill University, Montreal, QC H3A 0B8, Canada
- Pharmacology and Therapeutics, Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H3G 1Y6, Canada
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2
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Xue Y, Li J, Chen D, Zhao X, Hong L, Liu Y. Observation of structural switch in nascent SAM-VI riboswitch during transcription at single-nucleotide and single-molecule resolution. Nat Commun 2023; 14:2320. [PMID: 37087479 PMCID: PMC10122661 DOI: 10.1038/s41467-023-38042-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Accepted: 04/13/2023] [Indexed: 04/24/2023] Open
Abstract
Growing RNAs fold differently as they are transcribed, which modulates their finally adopted structures. Riboswitches regulate gene expression by structural change, which are sensitive to co-transcriptionally structural biology. Here we develop a strategy to track the structural change of RNAs during transcription at single-nucleotide and single-molecule resolution and use it to monitor individual transcripts of the SAM-VI riboswitch (riboSAM) as transcription proceeds, observing co-existence of five states in riboSAM. We report a bifurcated helix in one newly identified state from NMR and single-molecule FRET (smFRET) results, and its presence directs the translation inhibition in our cellular translation experiments. A model is proposed to illustrate the distinct switch patterns and gene-regulatory outcome of riboSAM when SAM is present or absent. Our strategy enables the precise mapping of RNAs' conformational landscape during transcription, and may combine with detection methods other than smFRET for structural studies of RNAs in general.
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Affiliation(s)
- Yanyan Xue
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Jun Li
- School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Dian Chen
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Xizhu Zhao
- Zhiyuan College, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Liang Hong
- School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, 200240, China.
- Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai, 200240, China.
- Shanghai Artificial Intelligence Laboratory, Shanghai, 200232, China.
| | - Yu Liu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.
- Shanghai Artificial Intelligence Laboratory, Shanghai, 200232, China.
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3
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Zheng L, Song Q, Xu X, Shen X, Li C, Li H, Chen H, Ren A. Structure-based insights into recognition and regulation of SAM-sensing riboswitches. SCIENCE CHINA. LIFE SCIENCES 2023; 66:31-50. [PMID: 36459353 DOI: 10.1007/s11427-022-2188-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 07/17/2022] [Indexed: 12/03/2022]
Abstract
Riboswitches are highly conserved RNA elements that located in the 5'-UTR of mRNAs, which undergo real-time structure conformational change to achieve the regulation of downstream gene expression by sensing their cognate ligands. S-adenosylmethionine (SAM) is a ubiquitous methyl donor for transmethylation reactions in all living organisms. SAM riboswitch is one of the most abundant riboswitches that bind to SAM with high affinity and selectivity, serving as regulatory modules in multiple metabolic pathways. To date, seven SAM-specific riboswitch classes that belong to four families, one SAM/SAH riboswitch and one SAH riboswitch have been identified. Each SAM riboswitch family has a well-organized tertiary core scaffold to support their unique ligand-specific binding pocket. In this review, we summarize the current research progress on the distribution, structure, ligand recognition and gene regulation mechanism of these SAM-related riboswitch families, and further discuss their evolutionary prospects and potential applications.
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Affiliation(s)
- Luqian Zheng
- Department of Gastroenterology, Department of Cardiology of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310058, China.,Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China.,The Eighth Affiliated Hospital, Sun Yat-sen University, Shenzhen, 518033, China
| | - Qianqian Song
- Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China
| | - Xiaochen Xu
- Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China
| | - Xin Shen
- Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China
| | - Chunyan Li
- Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China
| | - Hongcheng Li
- Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China
| | - Hao Chen
- Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China
| | - Aiming Ren
- Department of Gastroenterology, Department of Cardiology of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310058, China. .,Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China.
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4
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Alternative RNA Conformations: Companion or Combatant. Genes (Basel) 2022; 13:genes13111930. [DOI: 10.3390/genes13111930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 10/19/2022] [Accepted: 10/19/2022] [Indexed: 11/04/2022] Open
Abstract
RNA molecules, in one form or another, are involved in almost all aspects of cell physiology, as well as in disease development. The diversity of the functional roles of RNA comes from its intrinsic ability to adopt complex secondary and tertiary structures, rivaling the diversity of proteins. The RNA molecules form dynamic ensembles of many interconverting conformations at a timescale of seconds, which is a key for understanding how they execute their cellular functions. Given the crucial role of RNAs in various cellular processes, we need to understand the RNA molecules from a structural perspective. Central to this review are studies aimed at revealing the regulatory role of conformational equilibria in RNA in humans to understand genetic diseases such as cancer and neurodegenerative diseases, as well as in pathogens such as bacteria and viruses so as to understand the progression of infectious diseases. Furthermore, we also summarize the prior studies on the use of RNA structures as platforms for the rational design of small molecules for therapeutic applications.
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5
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Yadav R, Widom JR, Chauvier A, Walter NG. An anionic ligand snap-locks a long-range interaction in a magnesium-folded riboswitch. Nat Commun 2022; 13:207. [PMID: 35017489 PMCID: PMC8752731 DOI: 10.1038/s41467-021-27827-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Accepted: 12/02/2021] [Indexed: 01/22/2023] Open
Abstract
The archetypical transcriptional crcB fluoride riboswitch from Bacillus cereus is an intricately structured non-coding RNA element enhancing gene expression in response to toxic levels of fluoride. Here, we used single molecule FRET to uncover three dynamically interconverting conformations appearing along the transcription process: two distinct undocked states and one pseudoknotted docked state. We find that the fluoride anion specifically snap-locks the magnesium-induced, dynamically docked state. The long-range, nesting, single base pair A40-U48 acts as the main linchpin, rather than the multiple base pairs comprising the pseudoknot. We observe that the proximally paused RNA polymerase further fine-tunes the free energy to promote riboswitch docking. Finally, we show that fluoride binding at short transcript lengths is an early step toward partitioning folding into the docked conformation. These results reveal how the anionic fluoride ion cooperates with the magnesium-associated RNA to govern regulation of downstream genes needed for fluoride detoxification of the cell.
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Affiliation(s)
- Rajeev Yadav
- Single Molecule Analysis Group, Department of Chemistry and Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI, 48109, USA.,Department of Physics and Astronomy, Michigan State University, East Lansing, MI, 48824, USA
| | - Julia R Widom
- Single Molecule Analysis Group, Department of Chemistry and Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI, 48109, USA.,Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR, 97403, USA
| | - Adrien Chauvier
- Single Molecule Analysis Group, Department of Chemistry and Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Nils G Walter
- Single Molecule Analysis Group, Department of Chemistry and Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI, 48109, USA.
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Skeparnias I, Zhang J. Cooperativity and Interdependency between RNA Structure and RNA-RNA Interactions. Noncoding RNA 2021; 7:ncrna7040081. [PMID: 34940761 PMCID: PMC8704770 DOI: 10.3390/ncrna7040081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/09/2021] [Accepted: 12/10/2021] [Indexed: 11/16/2022] Open
Abstract
Complex RNA–RNA interactions are increasingly known to play key roles in numerous biological processes from gene expression control to ribonucleoprotein granule formation. By contrast, the nature of these interactions and characteristics of their interfaces, especially those that involve partially or wholly structured RNAs, remain elusive. Herein, we discuss different modalities of RNA–RNA interactions with an emphasis on those that depend on secondary, tertiary, or quaternary structure. We dissect recently structurally elucidated RNA–RNA complexes including RNA triplexes, riboswitches, ribozymes, and reverse transcription complexes. These analyses highlight a reciprocal relationship that intimately links RNA structure formation with RNA–RNA interactions. The interactions not only shape and sculpt RNA structures but also are enabled and modulated by the structures they create. Understanding this two-way relationship between RNA structure and interactions provides mechanistic insights into the expanding repertoire of noncoding RNA functions, and may inform the design of novel therapeutics that target RNA structures or interactions.
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Fairman CW, Lever AML, Kenyon JC. Evaluating RNA Structural Flexibility: Viruses Lead the Way. Viruses 2021; 13:v13112130. [PMID: 34834937 PMCID: PMC8624864 DOI: 10.3390/v13112130] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 10/12/2021] [Accepted: 10/18/2021] [Indexed: 12/11/2022] Open
Abstract
Our understanding of RNA structure has lagged behind that of proteins and most other biological polymers, largely because of its ability to adopt multiple, and often very different, functional conformations within a single molecule. Flexibility and multifunctionality appear to be its hallmarks. Conventional biochemical and biophysical techniques all have limitations in solving RNA structure and to address this in recent years we have seen the emergence of a wide diversity of techniques applied to RNA structural analysis and an accompanying appreciation of its ubiquity and versatility. Viral RNA is a particularly productive area to study in that this economy of function within a single molecule admirably suits the minimalist lifestyle of viruses. Here, we review the major techniques that are being used to elucidate RNA conformational flexibility and exemplify how the structure and function are, as in all biology, tightly linked.
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Affiliation(s)
| | - Andrew M. L. Lever
- Department of Medicine, Cambridge University, Level 5, Addenbrookes’ Hospital (Box 157), Cambridge CB2 0QQ, UK
- Correspondence: (A.M.L.L.); (J.C.K.); Tel.: +44-(0)-1223-747308 (A.M.L.L. & J.C.K.)
| | - Julia C. Kenyon
- Homerton College, University of Cambridge, Cambridge CB2 8PH, UK;
- Department of Medicine, Cambridge University, Level 5, Addenbrookes’ Hospital (Box 157), Cambridge CB2 0QQ, UK
- Correspondence: (A.M.L.L.); (J.C.K.); Tel.: +44-(0)-1223-747308 (A.M.L.L. & J.C.K.)
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Ariza-Mateos A, Nuthanakanti A, Serganov A. Riboswitch Mechanisms: New Tricks for an Old Dog. BIOCHEMISTRY (MOSCOW) 2021; 86:962-975. [PMID: 34488573 DOI: 10.1134/s0006297921080071] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Discovered almost twenty years ago, riboswitches turned out to be one of the most common regulatory systems in bacteria, with representatives found in eukaryotes and archaea. Unlike many other regulatory elements, riboswitches are entirely composed of RNA and capable of modulating expression of genes by direct binding of small cellular molecules. While bacterial riboswitches had been initially thought to control production of enzymes and transporters associated with small organic molecules via feedback regulatory circuits, later findings identified riboswitches directing expression of a wide range of genes and responding to various classes of molecules, including ions, signaling molecules, and others. The 5'-untranslated mRNA regions host a vast majority of riboswitches, which modulate transcription or translation of downstream genes through conformational rearrangements in the ligand-sensing domains and adjacent expression-controlling platforms. Over years, the repertoire of regulatory mechanisms employed by riboswitches has greatly expanded; most recent studies have highlighted the importance of alternative mechanisms, such as RNA degradation, for the riboswitch-mediated genetic circuits. This review discusses the plethora of bacterial riboswitch mechanisms and illustrates how riboswitches utilize different features and approaches to elicit various regulatory responses.
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Affiliation(s)
- Ascensión Ariza-Mateos
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Ashok Nuthanakanti
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Alexander Serganov
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016, USA.
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Lin Y, Liao YY, Huang RX, Li AZ, An SQ, Tang JL, Tang DJ. Extracellular Amylase Is Required for Full Virulence and Regulated by the Global Posttranscriptional Regulator RsmA in Xanthomonas campestris Pathovar campestris. PHYTOPATHOLOGY 2021; 111:1104-1113. [PMID: 33245253 DOI: 10.1094/phyto-08-20-0372-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
As with many phytopathogenic bacteria, the virulence of Xanthomonas campestris pv. campestris, the causal agent of black rot disease in cruciferous plants, relies on secretion of a suite of extracellular enzymes that includes cellulase (endoglucanase), pectinase, protease, and amylase. Although the role in virulence of a number of these enzymes has been assessed, the contribution of amylase to X. campestris pv. campestris virulence has yet to be established. In this work, we investigated both the role of extracellular amylase in X. campestris pv. campestris virulence and the control of its expression. Deletion of XC3487 (here renamed amyAXcc), a putative amylase-encoding gene from the genome of X. campestris pv. campestris strain 8004, resulted in a complete loss of extracellular amylase activity and significant reduction in virulence. The extracellular amylase activity and virulence of the amyAXcc mutant could be restored to the wild-type level by expressing amyAXcc in trans. These results demonstrated that amyAXcc is responsible for the extracellular amylase activity of X. campestris pv. campestris and indicated that extracellular amylase plays an important role in X. campestris pv. campestris virulence. We also found that the expression of amyAXcc is strongly induced by starch and requires activation by the global posttranscriptional regulator RsmA. RsmA binds specifically to the 5'-untranslated region of amyAXcc transcripts, suggesting that RsmA regulates amyAXcc directly at the posttranscriptional level. Unexpectedly, in addition to posttranscriptional regulation, the use of a transcriptional reporter demonstrated that RsmA also regulates amyAXcc expression at the transcriptional level, possibly by an indirect mechanism.
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Affiliation(s)
- Yan Lin
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, and College of Life Science and Technology, Guangxi University, Nanning, Guangxi 530004, China
| | - Yong-Yan Liao
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, and College of Life Science and Technology, Guangxi University, Nanning, Guangxi 530004, China
| | - Ru-Xia Huang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, and College of Life Science and Technology, Guangxi University, Nanning, Guangxi 530004, China
| | - Ai-Zhou Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, and College of Life Science and Technology, Guangxi University, Nanning, Guangxi 530004, China
| | - Shi-Qi An
- National Biofilms Innovation Centre, Biological Sciences, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Ji-Liang Tang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, and College of Life Science and Technology, Guangxi University, Nanning, Guangxi 530004, China
| | - Dong-Jie Tang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, and College of Life Science and Technology, Guangxi University, Nanning, Guangxi 530004, China
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Mutual Correlation between Non-Coding RNA and S-Adenosylmethionine in Human Cancer: Roles and Therapeutic Opportunities. Cancers (Basel) 2021; 13:cancers13133264. [PMID: 34209866 PMCID: PMC8268931 DOI: 10.3390/cancers13133264] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 06/25/2021] [Accepted: 06/26/2021] [Indexed: 12/13/2022] Open
Abstract
Simple Summary Non-coding RNAs and S-adenosylmethionine, the methyl donor required in all epigenetic methylation reactions, have emerged in recent years as crucial players in the modulation of gene expression in different types of human cancers. This review summarizes the most recent findings on reciprocal regulation between AdoMet and non-coding RNAs. AdoMet was found to exert anticancer activity through epigenetic regulation of non-coding RNAs, including microRNAs, long non-coding RNAs and circular RNAs. On the other hand, several microRNAs and long non-coding RNAs have been reported to display regulatory effects on the expression of genes involved in AdoMet synthesis and metabolism. Increasing knowledge on the relationship between AdoMet and non-coding RNAs will provide insights for further development of diagnostic and therapeutic strategies for cancer treatments. Abstract Epigenetics includes modifications in DNA methylation, histone and chromatin structure, and expression of non-coding RNAs (ncRNAs), especially microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). Knowledge of the relationships between S-adenosylmethionine (AdoMet or SAM), the universal methyl donor for all epigenetic methylation reactions and miRNAs or lncRNAs in human cancer may provide helpful insights for the development of new end more effective anticancer therapeutic approaches. In recent literature, a complex network of mutual interconnections between AdoMet and miRNAs or lncRNAs has been reported and discussed. Indeed, ncRNAs expression may be regulated by epigenetic mechanisms such as DNA and RNA methylation and histone modifications. On the other hand, miRNAs or lncRNAs may influence the epigenetic apparatus by modulating the expression of its enzymatic components at the post-transcriptional level. Understanding epigenetic mechanisms, such as dysregulation of miRNAs/lncRNAs and DNA methylation, has become of central importance in modern research. This review summarizes the recent findings on the mechanisms by which AdoMet and miRNA/lncRNA exert their bioactivity, providing new insights to develop innovative and more efficient anticancer strategies based on the interactions between these epigenetic modulators.
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