1
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Foong YH, Caldwell B, Thorvaldsen JL, Krapp C, Mesaros CA, Zhou W, Kohli RM, Bartolomei MS. TET1 displays catalytic and non-catalytic functions in the adult mouse cortex. Epigenetics 2024; 19:2374979. [PMID: 38970823 PMCID: PMC11229741 DOI: 10.1080/15592294.2024.2374979] [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: 01/23/2024] [Accepted: 06/26/2024] [Indexed: 07/08/2024] Open
Abstract
TET1/2/3 dioxygenases iteratively demethylate 5-methylcytosine, beginning with the formation of 5-hydroxymethylcytosine (5hmC). The post-mitotic brain maintains higher levels of 5hmC than most peripheral tissues, and TET1 ablation studies have underscored the critical role of TET1 in brain physiology. However, deletion of Tet1 precludes the disentangling of the catalytic and non-catalytic functions of TET1. Here, we dissect these functions of TET1 by comparing adult cortex of Tet1 wildtype (Tet1 WT), a novel Tet1 catalytically dead mutant (Tet1 HxD), and Tet1 knockout (Tet1 KO) mice. Using DNA methylation array, we uncover that Tet1 HxD and KO mutations perturb the methylation status of distinct subsets of CpG sites. Gene ontology (GO) analysis on specific differential 5hmC regions indicates that TET1's catalytic activity is linked to neuronal-specific functions. RNA-Seq further shows that Tet1 mutations predominantly impact the genes that are associated with alternative splicing. Lastly, we performed High-performance Liquid Chromatography Mass-Spectrometry lipidomics on WT and mutant cortices and uncover accumulation of lysophospholipids lysophosphatidylethanolamine and lysophosphatidylcholine in Tet1 HxD cortex. In summary, we show that Tet1 HxD does not completely phenocopy Tet1 KO, providing evidence that TET1 modulates distinct cortical functions through its catalytic and non-catalytic roles.
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Affiliation(s)
- Yee Hoon Foong
- Department of Cell and Developmental Biology, Perelman School of Medicine, Smilow Center for Translational Research, Philadelphia, PA, USA
| | - Blake Caldwell
- Department of Cell and Developmental Biology, Perelman School of Medicine, Smilow Center for Translational Research, Philadelphia, PA, USA
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
| | - Joanne L. Thorvaldsen
- Department of Cell and Developmental Biology, Perelman School of Medicine, Smilow Center for Translational Research, Philadelphia, PA, USA
| | - Christopher Krapp
- Department of Cell and Developmental Biology, Perelman School of Medicine, Smilow Center for Translational Research, Philadelphia, PA, USA
| | - Clementina A. Mesaros
- Translational Biomarkers Core, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Center of Excellence in Environmental Toxicology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Wanding Zhou
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Children’s Hospital of Philadelphia (CHOP), University of Pennsylvania, Philadelphia, PA, USA
- Penn Epigenetics Institute, Smilow Center for Translational Rsearch, Philadelphia, PA, USA
| | - Rahul M. Kohli
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Penn Epigenetics Institute, Smilow Center for Translational Rsearch, Philadelphia, PA, USA
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Marisa S. Bartolomei
- Department of Cell and Developmental Biology, Perelman School of Medicine, Smilow Center for Translational Research, Philadelphia, PA, USA
- Penn Epigenetics Institute, Smilow Center for Translational Rsearch, Philadelphia, PA, USA
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2
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Creighton CJ, Zhang F, Zhang Y, Castro P, Hu R, Islam M, Ghosh S, Ittmann M, Kwabi-Addo B. Comparative and integrative analysis of transcriptomic and epigenomic-wide DNA methylation changes in African American prostate cancer. Epigenetics 2023; 18:2180585. [PMID: 37279148 PMCID: PMC9980641 DOI: 10.1080/15592294.2023.2180585] [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: 09/21/2022] [Accepted: 02/01/2023] [Indexed: 02/24/2023] Open
Abstract
African American (AA) men have the highest incidence and mortality rate from Prostate cancer (PCa) than any other racial/ethnic group. To date, PCa genomic studies have largely under-represented tumour samples from AA men. We measured genome-wide DNA methylation in benign and tumor prostate tissues from AA men using the Illumina Infunium 850 K EPIC array. mRNA expression database from a subset of the AA biospecimen were used to assess correlation of transcriptome and methylation datasets. Genome-wide methylation analysis identified 11,460 probes that were significant (p < 0.01) and differentially methylated in AA PCa compared to normal prostate tissues and showed significant (p < 0.01) inverse-correlation with mRNA expression. Ingenuity pathway analysis and Gene Ontology analysis in our AA dataset compared with TCGA dataset showed similarities in methylation patterns: top candidate genes with significant hypermethylation and corresponding down-regulated gene expression were associated with biological pathways in hemidesmosome assembly, mammary gland development, epidermis development, hormone biosynthesis, and cell communication. In addition, top candidate genes with significant hypomethylation and corresponding up-regulated gene expression were associated with biological pathways in macrophage differentiation, cAMP-dependent protein kinase activity, protein destabilization, transcription co-repression, and fatty acid biosynthesis. In contrast, differences in genome-wide methylation in our AA dataset compared with TCGA dataset were enriched for genes in steroid signalling, immune signalling, chromatin structure remodelling and RNA processing. Overall, differential methylation of AMIGO3, IER3, UPB1, GRM7, TFAP2C, TOX2, PLSCR2, ZNF292, ESR2, MIXL1, BOLL, and FGF6 were significant and uniquely associated with PCa progression in our AA cohort.
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Affiliation(s)
- Chad J. Creighton
- Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, USA
| | - Flora Zhang
- Center for Women’s Studies, Colgate University, Hamilton, New York, USA
| | - Yiqun Zhang
- Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, USA
| | - Patricia Castro
- Department of Pathology and Immunology, Michael E. DeBakey Veterans Affairs Medical Center, Houston, Texas, USA
| | - Rong Hu
- Lombardi Comprehensive Cancer Center, Georgetown University, Washington, District of Columbia, USA
| | - Md Islam
- Lombardi Comprehensive Cancer Center, Georgetown University, Washington, District of Columbia, USA
| | - Somiranjan Ghosh
- Department of Biology, Howard University, Washington, Columbia, USA
| | - Michael Ittmann
- Department of Pathology and Immunology, Michael E. DeBakey Veterans Affairs Medical Center, Houston, Texas, USA
| | - Bernard Kwabi-Addo
- Department of Biochemistry and Molecular Biology, Howard University, Washington, Columbia, USA
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3
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Pascal C, Zonszain J, Hameiri O, Gargi-Levi C, Lev-Maor G, Tammer L, Levy T, Tarabeih A, Roy VR, Ben-Salmon S, Elbaz L, Eid M, Hakim T, Abu Rabe'a S, Shalev N, Jordan A, Meshorer E, Ast G. Human histone H1 variants impact splicing outcome by controlling RNA polymerase II elongation. Mol Cell 2023; 83:3801-3817.e8. [PMID: 37922872 DOI: 10.1016/j.molcel.2023.10.003] [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: 03/21/2023] [Revised: 08/17/2023] [Accepted: 10/05/2023] [Indexed: 11/07/2023]
Abstract
Histones shape chromatin structure and the epigenetic landscape. H1, the most diverse histone in the human genome, has 11 variants. Due to the high structural similarity between the H1s, their unique functions in transferring information from the chromatin to mRNA-processing machineries have remained elusive. Here, we generated human cell lines lacking up to five H1 subtypes, allowing us to characterize the genomic binding profiles of six H1 variants. Most H1s bind to specific sites, and binding depends on multiple factors, including GC content. The highly expressed H1.2 has a high affinity for exons, whereas H1.3 binds intronic sequences. H1s are major splicing regulators, especially of exon skipping and intron retention events, through their effects on the elongation of RNA polymerase II (RNAPII). Thus, H1 variants determine splicing fate by modulating RNAPII elongation.
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Affiliation(s)
- Corina Pascal
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Jonathan Zonszain
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ofir Hameiri
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Chen Gargi-Levi
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Galit Lev-Maor
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Luna Tammer
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Tamar Levy
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Anan Tarabeih
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Vanessa Rachel Roy
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Stav Ben-Salmon
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Liraz Elbaz
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Mireille Eid
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Tamar Hakim
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Salima Abu Rabe'a
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Nana Shalev
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Albert Jordan
- Instituto de Biologia Molecular de Barcelona (IBMB-CSIC), Carrer de Baldiri Reixac, 15, 08028 Barcelona, Spain
| | - Eran Meshorer
- Department of Genetics, The Alexander Silberman Institute of Life Sciences, Jerusalem 91904, Israel; Edmond and Lily Center for Brain Sciences (ELSC), The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Gil Ast
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
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4
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Hamilton DJ, Hein AE, Wuttke DS, Batey RT. The DNA binding high mobility group box protein family functionally binds RNA. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 14:e1778. [PMID: 36646476 PMCID: PMC10349909 DOI: 10.1002/wrna.1778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 12/22/2022] [Accepted: 12/27/2022] [Indexed: 01/18/2023]
Abstract
Nucleic acid binding proteins regulate transcription, splicing, RNA stability, RNA localization, and translation, together tailoring gene expression in response to stimuli. Upon discovery, these proteins are typically classified as either DNA or RNA binding as defined by their in vivo functions; however, recent evidence suggests dual DNA and RNA binding by many of these proteins. High mobility group box (HMGB) proteins have a DNA binding HMGB domain, act as transcription factors and chromatin remodeling proteins, and are increasingly understood to interact with RNA as means to regulate gene expression. Herein, multiple layers of evidence that the HMGB family are dual DNA and RNA binding proteins is comprehensively reviewed. For example, HMGB proteins directly interact with RNA in vitro and in vivo, are localized to RNP granules involved in RNA processing, and their protein interactors are enriched in RNA binding proteins involved in RNA metabolism. Importantly, in cell-based systems, HMGB-RNA interactions facilitate protein-protein interactions, impact splicing outcomes, and modify HMGB protein genomic or cellular localization. Misregulation of these HMGB-RNA interactions are also likely involved in human disease. This review brings to light that as a family, HMGB proteins are likely to bind RNA which is essential to HMGB protein biology. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Protein-RNA Recognition RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
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5
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Jin B, Zhu J, Pan T, Yang Y, Liang L, Zhou Y, Zhang T, Teng Y, Wang Z, Wang X, Tian Q, Guo B, Li H, Chen T. MEN1 is a regulator of alternative splicing and prevents R-loop-induced genome instability through suppression of RNA polymerase II elongation. Nucleic Acids Res 2023; 51:7951-7971. [PMID: 37395406 PMCID: PMC10450199 DOI: 10.1093/nar/gkad548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 06/02/2023] [Accepted: 06/15/2023] [Indexed: 07/04/2023] Open
Abstract
The fidelity of alternative splicing (AS) patterns is essential for growth development and cell fate determination. However, the scope of the molecular switches that regulate AS remains largely unexplored. Here we show that MEN1 is a previously unknown splicing regulatory factor. MEN1 deletion resulted in reprogramming of AS patterns in mouse lung tissue and human lung cancer cells, suggesting that MEN1 has a general function in regulating alternative precursor mRNA splicing. MEN1 altered exon skipping and the abundance of mRNA splicing isoforms of certain genes with suboptimal splice sites. Chromatin immunoprecipitation and chromosome walking assays revealed that MEN1 favored the accumulation of RNA polymerase II (Pol II) in regions encoding variant exons. Our data suggest that MEN1 regulates AS by slowing the Pol II elongation rate and that defects in these processes trigger R-loop formation, DNA damage accumulation and genome instability. Furthermore, we identified 28 MEN1-regulated exon-skipping events in lung cancer cells that were closely correlated with survival in patients with lung adenocarcinoma, and MEN1 deficiency sensitized lung cancer cells to splicing inhibitors. Collectively, these findings led to the identification of a novel biological role for menin in maintaining AS homeostasis and link this role to the regulation of cancer cell behavior.
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Affiliation(s)
- Bangming Jin
- Department of Physiology, School of Basic Medical Sciences, Guizhou Medical University, 550025 Guiyang, China
- Department of Surgery, Affiliated Hospital of Guizhou Medical University, 550025 Guiyang, China
- Transformation Engineering Research Center of Chronic Disease Diagnosis and Treatment, Guizhou Medical University, Guiyang, China
- Guizhou Provincial Key Laboratory of Pathogenesis and Drug Research on Common Chronic Diseases, Guizhou Medical University, 550025 Guiyang, China
| | - Jiamei Zhu
- Department of Physiology, School of Basic Medical Sciences, Guizhou Medical University, 550025 Guiyang, China
- Transformation Engineering Research Center of Chronic Disease Diagnosis and Treatment, Guizhou Medical University, Guiyang, China
- Guizhou Provincial Key Laboratory of Pathogenesis and Drug Research on Common Chronic Diseases, Guizhou Medical University, 550025 Guiyang, China
| | - Ting Pan
- Department of Physiology, School of Basic Medical Sciences, Guizhou Medical University, 550025 Guiyang, China
- Transformation Engineering Research Center of Chronic Disease Diagnosis and Treatment, Guizhou Medical University, Guiyang, China
- Guizhou Provincial Key Laboratory of Pathogenesis and Drug Research on Common Chronic Diseases, Guizhou Medical University, 550025 Guiyang, China
| | - Yunqiao Yang
- Department of Physiology, School of Basic Medical Sciences, Guizhou Medical University, 550025 Guiyang, China
- Department of Surgery, Affiliated Hospital of Guizhou Medical University, 550025 Guiyang, China
- Transformation Engineering Research Center of Chronic Disease Diagnosis and Treatment, Guizhou Medical University, Guiyang, China
- Guizhou Provincial Key Laboratory of Pathogenesis and Drug Research on Common Chronic Diseases, Guizhou Medical University, 550025 Guiyang, China
| | - Li Liang
- Department of Physiology, School of Basic Medical Sciences, Guizhou Medical University, 550025 Guiyang, China
- Transformation Engineering Research Center of Chronic Disease Diagnosis and Treatment, Guizhou Medical University, Guiyang, China
- Guizhou Provincial Key Laboratory of Pathogenesis and Drug Research on Common Chronic Diseases, Guizhou Medical University, 550025 Guiyang, China
| | - Yuxia Zhou
- Department of Physiology, School of Basic Medical Sciences, Guizhou Medical University, 550025 Guiyang, China
- Transformation Engineering Research Center of Chronic Disease Diagnosis and Treatment, Guizhou Medical University, Guiyang, China
- Guizhou Provincial Key Laboratory of Pathogenesis and Drug Research on Common Chronic Diseases, Guizhou Medical University, 550025 Guiyang, China
| | - Tuo Zhang
- Department of Physiology, School of Basic Medical Sciences, Guizhou Medical University, 550025 Guiyang, China
- Transformation Engineering Research Center of Chronic Disease Diagnosis and Treatment, Guizhou Medical University, Guiyang, China
- Guizhou Provincial Key Laboratory of Pathogenesis and Drug Research on Common Chronic Diseases, Guizhou Medical University, 550025 Guiyang, China
| | - Yin Teng
- Department of Surgery, Affiliated Hospital of Guizhou Medical University, 550025 Guiyang, China
- Guizhou Institute of Precision Medicine, Affiliated Hospital of Guizhou Medical University, 550025 Guiyang, China
| | - Ziming Wang
- Department of Physiology, School of Basic Medical Sciences, Guizhou Medical University, 550025 Guiyang, China
- Transformation Engineering Research Center of Chronic Disease Diagnosis and Treatment, Guizhou Medical University, Guiyang, China
- Guizhou Provincial Key Laboratory of Pathogenesis and Drug Research on Common Chronic Diseases, Guizhou Medical University, 550025 Guiyang, China
| | - Xuyan Wang
- Department of Physiology, School of Basic Medical Sciences, Guizhou Medical University, 550025 Guiyang, China
- Transformation Engineering Research Center of Chronic Disease Diagnosis and Treatment, Guizhou Medical University, Guiyang, China
- Guizhou Provincial Key Laboratory of Pathogenesis and Drug Research on Common Chronic Diseases, Guizhou Medical University, 550025 Guiyang, China
| | - Qianting Tian
- Transformation Engineering Research Center of Chronic Disease Diagnosis and Treatment, Guizhou Medical University, Guiyang, China
- Guizhou Institute of Precision Medicine, Affiliated Hospital of Guizhou Medical University, 550025 Guiyang, China
| | - Bing Guo
- Department of Physiology, School of Basic Medical Sciences, Guizhou Medical University, 550025 Guiyang, China
- Transformation Engineering Research Center of Chronic Disease Diagnosis and Treatment, Guizhou Medical University, Guiyang, China
- Guizhou Provincial Key Laboratory of Pathogenesis and Drug Research on Common Chronic Diseases, Guizhou Medical University, 550025 Guiyang, China
| | - Haiyang Li
- Department of Surgery, Affiliated Hospital of Guizhou Medical University, 550025 Guiyang, China
- Guizhou Institute of Precision Medicine, Affiliated Hospital of Guizhou Medical University, 550025 Guiyang, China
| | - Tengxiang Chen
- Department of Physiology, School of Basic Medical Sciences, Guizhou Medical University, 550025 Guiyang, China
- Department of Surgery, Affiliated Hospital of Guizhou Medical University, 550025 Guiyang, China
- Transformation Engineering Research Center of Chronic Disease Diagnosis and Treatment, Guizhou Medical University, Guiyang, China
- Guizhou Provincial Key Laboratory of Pathogenesis and Drug Research on Common Chronic Diseases, Guizhou Medical University, 550025 Guiyang, China
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6
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Zhai R, Ruan K, Perez GF, Kubat M, Liu J, Hofacker I, Wuchty S. MicroRNA-Mediated Obstruction of Stem-loop Alternative Splicing (MIMOSAS): a global mechanism for the regulation of alternative splicing. RESEARCH SQUARE 2023:rs.3.rs-2977025. [PMID: 37546804 PMCID: PMC10402249 DOI: 10.21203/rs.3.rs-2977025/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
While RNA secondary structures are critical to regulate alternative splicing of long-range pre-mRNA, the factors that modulate RNA structure and interfere with the recognition of the splice sites are largely unknown. Previously, we identified a small, non-coding microRNA that sufficiently affects stable stem structure formation of Nmnat pre-mRNA to regulate the outcomes of alternative splicing. However, the fundamental question remains whether such microRNA-mediated interference with RNA secondary structures is a global molecular mechanism for regulating mRNA splicing. We designed and refined a bioinformatic pipeline to predict candidate microRNAs that potentially interfere with pre-mRNA stem-loop structures, and experimentally verified splicing predictions of three different long-range pre-mRNAs in the Drosophila model system. Specifically, we observed that microRNAs can either disrupt or stabilize stem-loop structures to influence splicing outcomes. Our study suggests that MicroRNA-Mediated Obstruction of Stem-loop Alternative Splicing (MIMOSAS) is a novel regulatory mechanism for the transcriptome-wide regulation of alternative splicing, increases the repertoire of microRNA function and further indicates cellular complexity of post-transcriptional regulation.
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Affiliation(s)
| | - Kai Ruan
- University of Miami, Miller School of Medicine
| | | | | | - Jiaqi Liu
- University of Miami Miller School of Medicine
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7
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Ruan K, Perez GF, Liu J, Kubat M, Hofacker I, Wuchty S, Zhai RG. MicroRNA-Mediated Obstruction of Stem-loop Alternative Splicing (MIMOSAS): a global mechanism for the regulation of alternative splicing. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.14.536877. [PMID: 37425843 PMCID: PMC10327045 DOI: 10.1101/2023.04.14.536877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
While RNA secondary structures are critical to regulate alternative splicing of long-range pre-mRNA, the factors that modulate RNA structure and interfere with the recognition of the splice sites are largely unknown. Previously, we identified a small, non-coding microRNA that sufficiently affects stable stem structure formation of Nmnat pre-mRNA to regulate the outcomes of alternative splicing. However, the fundamental question remains whether such microRNA-mediated interference with RNA secondary structures is a global molecular mechanism for regulating mRNA splicing. We designed and refined a bioinformatic pipeline to predict candidate microRNAs that potentially interfere with pre-mRNA stem-loop structures, and experimentally verified splicing predictions of three different long-range pre-mRNAs in the Drosophila model system. Specifically, we observed that microRNAs can either disrupt or stabilize stem-loop structures to influence splicing outcomes. Our study suggests that MicroRNA-Mediated Obstruction of Stem-loop Alternative Splicing (MIMOSAS) is a novel regulatory mechanism for the transcriptome-wide regulation of alternative splicing, increases the repertoire of microRNA function and further indicates cellular complexity of post-transcriptional regulation. One-Sentence Summary MicroRNA-Mediated Obstruction of Stem-loop Alternative Splicing (MIMOSAS) is a novel regulatory mechanism for the transcriptome-wide regulation of alternative splicing.
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8
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Sergeeva A, Davydova K, Perenkov A, Vedunova M. Mechanisms of human DNA methylation, alteration of methylation patterns in physiological processes and oncology. Gene 2023:147487. [PMID: 37211289 DOI: 10.1016/j.gene.2023.147487] [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: 03/02/2023] [Revised: 05/05/2023] [Accepted: 05/11/2023] [Indexed: 05/23/2023]
Abstract
DNA methylation is one of the epigenetic modifications of the genome, the essence of which is the attachment of a methyl group to nitrogenous bases. In the eukaryote genome, cytosine is methylated in the vast majority of cases. About 98% of cytosines are methylated as part of CpG dinucleotides. They, in turn, form CpG islands, which are clusters of these dinucleotides. Islands located in the regulatory elements of genes are in particular interest. They are assumed to play an important role in the regulation of gene expression in humans. Besides that, cytosine methylation serves the functions of genomic imprinting, transposon suppression, epigenetic memory maintenance, X- chromosome inactivation, and embryonic development. Of particular interest are the enzymatic processes of methylation and demethylation. The methylation process always depends on the work of enzymatic complexes and is very precisely regulated. The methylation process largely depends on the functioning of three groups of enzymes: writers, readers and erasers. Writers include proteins of the DNMT family, readers are proteins containing the MBD, BTB/POZ or SET- and RING-associated domains and erasers are proteins of the TET family. Whereas demethylation can be performed not only by enzymatic complexes, but also passively during DNA replication. Hence, the maintenance of DNA methylation is important. Changes in methylation patterns are observed during embryonic development, aging, and cancers. In both aging and cancer, massive hypomethylation of the genome with local hypermethylation is observed. In this review, we will review the current understanding of the mechanisms of DNA methylation and demethylation in humans, the structure and distribution of CpG islands, the role of methylation in the regulation of gene expression, embryogenesis, aging, and cancer development.
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Affiliation(s)
- A Sergeeva
- Institute of Biology and Biomedicine, National Research Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, 603022, Russia
| | - K Davydova
- Institute of Biology and Biomedicine, National Research Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, 603022, Russia
| | - A Perenkov
- Institute of Biology and Biomedicine, National Research Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, 603022, Russia
| | - M Vedunova
- Institute of Biology and Biomedicine, National Research Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, 603022, Russia
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9
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Jian Y, Chen X, Sun K, Liu Z, Cheng D, Cao J, Liu J, Cheng X, Wu L, Zhang F, Luo Y, Hahn M, Ma Z, Yin Y. SUMOylation regulates pre-mRNA splicing to overcome DNA damage in fungi. THE NEW PHYTOLOGIST 2023; 237:2298-2315. [PMID: 36539920 DOI: 10.1111/nph.18692] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 12/09/2022] [Indexed: 06/17/2023]
Abstract
Pathogenic fungi are subject to DNA damage stress derived from host immune responses during infection. Small ubiquitin-like modifier (SUMO) modification and precursor (pre)-mRNA splicing are both involved in DNA damage response (DDR). However, the mechanisms of how SUMOylation and splicing coordinated in DDR remain largely unknown. Combining with biochemical analysis, RNA-Seq method, and biological analysis, we report that SUMO pathway participates in DDR and virulence in Fusarium graminearum, a causal agent of Fusarium head blight of cereal crops world-wide. Interestingly, a key transcription factor FgSR is SUMOylated upon DNA damage stress. SUMOylation regulates FgSR nuclear-cytoplasmic partitioning and its phosphorylation by FgMec1, and promotes its interaction with chromatin remodeling complex SWI/SNF for activating the expression of DDR-related genes. Moreover, the SWI/SNF complex was found to further recruit splicing-related NineTeen Complex, subsequently modulates pre-mRNA splicing during DDR. Our findings reveal a novel function of SUMOylation in DDR by regulating a transcription factor to orchestrate gene expression and pre-mRNA splicing to overcome DNA damage during the infection of F. graminearum, which advances the understanding of the delicate regulation of DDR by SUMOylation in pathogenic fungi, and extends the knowledge of cooperation of SUMOylation and pre-mRNA splicing in DDR in eukaryotes.
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Affiliation(s)
- Yunqing Jian
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Xia Chen
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Kewei Sun
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Zunyong Liu
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Danni Cheng
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Jie Cao
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, 310058, China
| | - Jianzhao Liu
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, 310058, China
| | - Xiaofei Cheng
- Key Laboratory of Germplasm Enhancement, Physiology and Ecology of Food Crops in Cold Region of Chinese Education Ministry, College of Agriculture, Northeast Agricultural University, Harbin, 150030, China
| | - Liang Wu
- Institute of Crop Science, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Feng Zhang
- Key Laboratory of Pesticide, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yuming Luo
- Jiangsu Key Laboratory for Eco-Agricultural Biotechnology around Hongze Lake, Jiangsu Collaborative Innovation Center of Regional Modern Agriculture and Environmental Protection, Huaiyin Normal University, Huai'an, 223300, China
| | - Matthias Hahn
- Department of Biology, University of Kaiserslautern, PO Box 3049, 67653, Kaiserslautern, Germany
| | - Zhonghua Ma
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Yanni Yin
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
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10
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Muñoz JC, Beckerman I, Choudhary R, Bouvier LA, Muñoz MJ. DNA Damage-Induced RNAPII Degradation and Its Consequences in Gene Expression. Genes (Basel) 2022; 13:1951. [PMID: 36360188 PMCID: PMC9689695 DOI: 10.3390/genes13111951] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 10/13/2022] [Accepted: 10/20/2022] [Indexed: 08/27/2023] Open
Abstract
RPB1, the major and catalytic subunit of human RNA Polymerase II (RNAPII), is specifically degraded by the ubiquitin-proteasome system upon induction of DNA damage by different agents, such as ultraviolet (UV) light. The "last resort" model of RNAPII degradation states that a persistently stalled RNAPII is degraded at the site of the DNA lesion in order to facilitate access to Nucleotide Excision Repair (NER) factors, thereby promoting repair in template strands of active genes. Recent identification and mutation of the lysine residue involved in RPB1 ubiquitylation and degradation unveiled the relevance of RNAPII levels in the control of gene expression. Inhibition of RNAPII degradation after UV light exposure enhanced RNAPII loading onto chromatin, demonstrating that the mere concentration of RNAPII shapes the gene expression response. In this review, we discuss the role of RNAPII ubiquitylation in NER-dependent repair, recent advances in RPB1 degradation mechanisms and its consequences in gene expression under stress, both in normal and repair deficient cells.
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Affiliation(s)
- Juan Cristobal Muñoz
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Ciudad Universitaria, Buenos Aires C1428EHA, Argentina
| | - Inés Beckerman
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Ciudad Universitaria, Buenos Aires C1428EHA, Argentina
| | - Ramveer Choudhary
- IFOM ETS—The AIRC Institute of Molecular Oncology, Via Adamello, 16, 20139 Milan, Italy
| | - León Alberto Bouvier
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Ciudad Universitaria, Buenos Aires C1428EHA, Argentina
| | - Manuel J. Muñoz
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Ciudad Universitaria, Buenos Aires C1428EHA, Argentina
- IFOM ETS—The AIRC Institute of Molecular Oncology, Via Adamello, 16, 20139 Milan, Italy
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires C1428EHA, Argentina
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11
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Jian Y, Shim WB, Ma Z. Multiple functions of SWI/SNF chromatin remodeling complex in plant-pathogen interactions. STRESS BIOLOGY 2021; 1:18. [PMID: 37676626 PMCID: PMC10442046 DOI: 10.1007/s44154-021-00019-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Accepted: 11/22/2021] [Indexed: 09/08/2023]
Abstract
The SWI/SNF chromatin remodeling complex utilizes the energy of ATP hydrolysis to facilitate chromatin access and plays essential roles in DNA-based events. Studies in animals, plants and fungi have uncovered sophisticated regulatory mechanisms of this complex that govern development and various stress responses. In this review, we summarize the composition of SWI/SNF complex in eukaryotes and discuss multiple functions of the SWI/SNF complex in regulating gene transcription, mRNA splicing, and DNA damage response. Our review further highlights the importance of SWI/SNF complex in regulating plant immunity responses and fungal pathogenesis. Finally, the potentials in exploiting chromatin remodeling for management of crop disease are presented.
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Affiliation(s)
- Yunqing Jian
- State Key Laboratory of Rice Biology, and Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Won-Bo Shim
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, USA
| | - Zhonghua Ma
- State Key Laboratory of Rice Biology, and Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, China.
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12
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Dey P, Mattick JS. High frequency of intron retention and clustered H3K4me3-marked nucleosomes in short first introns of human long non-coding RNAs. Epigenetics Chromatin 2021; 14:45. [PMID: 34579770 PMCID: PMC8477579 DOI: 10.1186/s13072-021-00419-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 08/27/2021] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND It is established that protein-coding exons are preferentially localized in nucleosomes. To examine whether the same is true for non-coding exons, we analysed nucleosome occupancy in and adjacent to internal exons in genes encoding long non-coding RNAs (lncRNAs) in human CD4+ T cells and K562 cells. RESULTS We confirmed that internal exons in lncRNAs are preferentially associated with nucleosomes, but also observed an elevated signal from H3K4me3-marked nucleosomes in the sequences upstream of these exons. Examination of 200 genomic lncRNA loci chosen at random across all chromosomes showed that high-density regions of H3K4me3-marked nucleosomes, which we term 'slabs', are associated with genomic regions exhibiting intron retention. These retained introns occur in over 50% of lncRNAs examined and are mostly first introns with an average length of just 354 bp, compared to the average length of all human introns of 6355 and 7987 bp in mRNAs and lncRNAs, respectively. Removal of short introns from the dataset abrogated the high upstream H3K4me3 signal, confirming that the association of slabs and short lncRNA introns with intron retention holds genome-wide. The high upstream H3K4me3 signal is also associated with alternatively spliced exons, known to be prominent in lncRNAs. This phenomenon was not observed with mRNAs. CONCLUSIONS There is widespread intron retention and clustered H3K4me3-marked nucleosomes in short first introns of human long non-coding RNAs, which raises intriguing questions about the relationship of IR to lncRNA function and chromatin organization.
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Affiliation(s)
- Pinki Dey
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, 2052, Sydney, Australia
| | - John S Mattick
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, 2052, Sydney, Australia.
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13
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Schärfen L, Neugebauer KM. Transcription Regulation Through Nascent RNA Folding. J Mol Biol 2021; 433:166975. [PMID: 33811916 DOI: 10.1016/j.jmb.2021.166975] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 03/23/2021] [Accepted: 03/24/2021] [Indexed: 12/14/2022]
Abstract
Folding of RNA into secondary structures through intramolecular base pairing determines an RNA's three-dimensional architecture and associated function. Simple RNA structures like stem loops can provide specialized functions independent of coding capacity, such as protein binding, regulation of RNA processing and stability, stimulation or inhibition of translation. RNA catalysis is dependent on tertiary structures found in the ribosome, tRNAs and group I and II introns. While the extent to which non-coding RNAs contribute to cellular maintenance is generally appreciated, the fact that both non-coding and coding RNA can assume relevant structural states has only recently gained attention. In particular, the co-transcriptional folding of nascent RNA of all classes has the potential to regulate co-transcriptional processing, RNP (ribonucleoprotein particle) formation, and transcription itself. Riboswitches are established examples of co-transcriptionally folded coding RNAs that directly regulate transcription, mainly in prokaryotes. Here we discuss recent studies in both prokaryotes and eukaryotes showing that structure formation may carry a more widespread regulatory logic during RNA synthesis. Local structures forming close to the catalytic center of RNA polymerases have the potential to regulate transcription by reducing backtracking. In addition, stem loops or more complex structures may alter co-transcriptional RNA processing or its efficiency. Several examples of functional structures have been identified to date, and this review provides an overview of physiologically distinct processes where co-transcriptionally folded RNA plays a role. Experimental approaches such as single-molecule FRET and in vivo structural probing to further advance our insight into the significance of co-transcriptional structure formation are discussed.
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Affiliation(s)
- Leonard Schärfen
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Karla M Neugebauer
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA.
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14
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Pisignano G, Ladomery M. Epigenetic Regulation of Alternative Splicing: How LncRNAs Tailor the Message. Noncoding RNA 2021; 7:ncrna7010021. [PMID: 33799493 PMCID: PMC8005942 DOI: 10.3390/ncrna7010021] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 02/05/2021] [Accepted: 02/22/2021] [Indexed: 12/23/2022] Open
Abstract
Alternative splicing is a highly fine-tuned regulated process and one of the main drivers of proteomic diversity across eukaryotes. The vast majority of human multi-exon genes is alternatively spliced in a cell type- and tissue-specific manner, and defects in alternative splicing can dramatically alter RNA and protein functions and lead to disease. The eukaryotic genome is also intensively transcribed into long and short non-coding RNAs which account for up to 90% of the entire transcriptome. Over the years, lncRNAs have received considerable attention as important players in the regulation of cellular processes including alternative splicing. In this review, we focus on recent discoveries that show how lncRNAs contribute significantly to the regulation of alternative splicing and explore how they are able to shape the expression of a diverse set of splice isoforms through several mechanisms. With the increasing number of lncRNAs being discovered and characterized, the contribution of lncRNAs to the regulation of alternative splicing is likely to grow significantly.
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Affiliation(s)
- Giuseppina Pisignano
- Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
- Correspondence: (G.P.); (M.L.)
| | - Michael Ladomery
- Faculty of Health and Applied Sciences, University of the West of England, Coldharbour Lane, Frenchay, Bristol BS16 1QY, UK
- Correspondence: (G.P.); (M.L.)
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15
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Role of promoters in regulating alternative splicing. Gene 2021; 782:145523. [PMID: 33667606 DOI: 10.1016/j.gene.2021.145523] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 12/31/2020] [Accepted: 02/09/2021] [Indexed: 01/19/2023]
Abstract
Alternative splicing (AS) plays a critical role in enhancing proteome complexity in higher eukaryotes. Almost all the multi intron-containing genes undergo AS in humans. Splicing mainly occurs co-transcriptionally, where RNA polymerase II (RNA pol II) plays a crucial role in coordinating transcription and pre-mRNA splicing. Aberrant AS leads to non-functional proteins causative in various pathophysiological conditions such as cancers, neurodegenerative diseases, and muscular dystrophies. Transcription and pre-mRNA splicing are deeply interconnected and can influence each other's functions. Several studies evinced that specific promoters employed by RNA pol II dictate the RNA processing decisions. Promoter-specific recruitment of certain transcriptional factors or transcriptional coactivators influences splicing, and the extent to which these factors affect splicing has not been discussed in detail. Here, in this review, various DNA-binding proteins and their influence on promoter-specific AS are extensively discussed. Besides, this review highlights how the promoter-specific epigenetic changes might regulate AS.
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16
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Fang S, Hou X, Qiu K, He R, Feng X, Liang X. The occurrence and function of alternative splicing in fungi. FUNGAL BIOL REV 2020. [DOI: 10.1016/j.fbr.2020.10.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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17
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Sun X, Tian Y, Wang J, Sun Z, Zhu Y. Genome-wide analysis reveals the association between alternative splicing and DNA methylation across human solid tumors. BMC Med Genomics 2020; 13:4. [PMID: 31906954 PMCID: PMC6945449 DOI: 10.1186/s12920-019-0654-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 12/24/2019] [Indexed: 12/13/2022] Open
Abstract
Background Dysregulation of alternative splicing (AS) is a critical signature of cancer. However, the regulatory mechanisms of cancer-specific AS events, especially the impact of DNA methylation, are poorly understood. Methods By using The Cancer Genome Atlas (TCGA) SpliceSeq and TCGA data for ten solid tumor types, association analysis was performed to characterize the potential link between cancer-specific AS and DNA methylation. Functional and pathway enrichment analyses were performed, and the protein-protein interaction (PPI) network was constructed with the String website. The prognostic analysis was carried out with multivariate Cox regressions models. Results 15,818 AS events in 3955 annotated genes were identified across ten solid tumor types. The different DNA methylation patterns between tumor and normal tissues at the corresponding alternative spliced exon boundaries were shown, and 51.3% of CpG sites (CpGs) revealed hypomethylated in tumors. Notably, 607 CpGs were found to be highly correlated with 369 cancer-specific AS events after permutation tests. Among them, the hypomethylated CpGs account for 52.7%, and the number of down-regulated exons was 173. Furthermore, we found 38 AS events in 35 genes could serve as new molecular biomarkers to predict patient survival. Conclusions Our study described the relationship between DNA methylation and AS events across ten human solid tumor types and provided new insights into intragenic DNA methylation and exon usage during the AS process.
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Affiliation(s)
- Xiaohui Sun
- Department of Epidemiology & Biostatistics, School of Public Health, Zhejiang University, Hangzhou, 310058, Zhejiang, China
| | - Yiping Tian
- Department of Pathology, Zhejiang Cancer Hospital, Hangzhou, 310022, China
| | - Jianming Wang
- Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey, Robert Wood Johnson Medical School, Rutgers, the State University of New Jersey, New Brunswick, 08901, USA
| | - Zeyuan Sun
- Department of Health Related Social and Behavioral Science, West China School of Public Health, Sichuan University, Chengdu, 610041, China
| | - Yimin Zhu
- Department of Epidemiology & Biostatistics, School of Public Health, Zhejiang University, Hangzhou, 310058, Zhejiang, China.
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18
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Idris M, Harmston N, Petretto E, Madan B, Virshup DM. Broad regulation of gene isoform expression by Wnt signaling in cancer. RNA (NEW YORK, N.Y.) 2019; 25:1696-1713. [PMID: 31506381 PMCID: PMC6859862 DOI: 10.1261/rna.071506.119] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 09/06/2019] [Indexed: 05/08/2023]
Abstract
Differential gene isoform expression is a ubiquitous mechanism to enhance proteome diversity and maintain cell homeostasis. Mechanisms such as splicing that drive gene isoform variability are highly dynamic and responsive to changes in cell signaling pathways. Wnt/β-catenin signaling has profound effects on cell activity and cell fate and is known to modify several splicing events by altering the expression of individual splicing factors. However, a global assessment of how extensively Wnt signaling regulates splicing and other mechanisms that determine mRNA isoform composition in cancer is lacking. We used deep time-resolved RNA-seq in two independent in vivo Wnt-addicted tumor models during treatment with the potent Wnt inhibitor ETC-159 and examined Wnt regulated splicing events and splicing regulators. We found 1025 genes that underwent Wnt regulated variable exon usage leading to isoform expression changes. This was accompanied by extensive Wnt regulated changes in the expression of splicing regulators. Many of these Wnt regulated events were conserved in multiple human cancers, and many were linked to previously defined cancer-associated splicing quantitative trait loci. This suggests that the Wnt regulated splicing events are components of fundamental oncogenic processes. These findings demonstrate the wide-ranging effects of Wnt signaling on the isoform composition of the cell and provides an extensive resource of expression changes of splicing regulators and gene isoforms regulated by Wnt signaling.
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Affiliation(s)
- Muhammad Idris
- Programme in Cancer and Stem Cell Biology, Duke-NUS Medical School, Singapore, 169857
| | - Nathan Harmston
- Programme in Cancer and Stem Cell Biology, Duke-NUS Medical School, Singapore, 169857
- Centre for Computational Biology and Programme in Cardiovascular and Metabolic Disorders, Duke-NUS Medical School, Singapore, 169857
- Science Division, Yale-NUS College, Singapore, 138527
| | - Enrico Petretto
- Centre for Computational Biology and Programme in Cardiovascular and Metabolic Disorders, Duke-NUS Medical School, Singapore, 169857
| | - Babita Madan
- Programme in Cancer and Stem Cell Biology, Duke-NUS Medical School, Singapore, 169857
| | - David M Virshup
- Programme in Cancer and Stem Cell Biology, Duke-NUS Medical School, Singapore, 169857
- Department of Pediatrics, Duke University School of Medicine, Durham, North Carolina 27705, USA
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19
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Yu S, Jordán-Pla A, Gañez-Zapater A, Jain S, Rolicka A, Östlund Farrants AK, Visa N. SWI/SNF interacts with cleavage and polyadenylation factors and facilitates pre-mRNA 3' end processing. Nucleic Acids Res 2019; 46:8557-8573. [PMID: 29860334 PMCID: PMC6144808 DOI: 10.1093/nar/gky438] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 05/08/2018] [Indexed: 12/12/2022] Open
Abstract
SWI/SNF complexes associate with genes and regulate transcription by altering the chromatin at the promoter. It has recently been shown that these complexes play a role in pre-mRNA processing by associating at alternative splice sites. Here, we show that SWI/SNF complexes are involved also in pre-mRNA 3′ end maturation by facilitating 3′ end cleavage of specific pre-mRNAs. Comparative proteomics show that SWI/SNF ATPases interact physically with subunits of the cleavage and polyadenylation complexes in fly and human cells. In Drosophila melanogaster, the SWI/SNF ATPase Brahma (dBRM) interacts with the CPSF6 subunit of cleavage factor I. We have investigated the function of dBRM in 3′ end formation in S2 cells by RNA interference, single-gene analysis and RNA sequencing. Our data show that dBRM facilitates pre-mRNA cleavage in two different ways: by promoting the association of CPSF6 to the cleavage region and by stabilizing positioned nucleosomes downstream of the cleavage site. These findings show that SWI/SNF complexes play a role also in the cleavage of specific pre-mRNAs in animal cells.
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Affiliation(s)
- Simei Yu
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-10691 Stockholm, Sweden
| | - Antonio Jordán-Pla
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-10691 Stockholm, Sweden
| | - Antoni Gañez-Zapater
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-10691 Stockholm, Sweden
| | - Shruti Jain
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-10691 Stockholm, Sweden
| | - Anna Rolicka
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-10691 Stockholm, Sweden
| | - Ann-Kristin Östlund Farrants
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-10691 Stockholm, Sweden
| | - Neus Visa
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-10691 Stockholm, Sweden
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20
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Davis-Turak J, Johnson TL, Hoffmann A. Mathematical modeling identifies potential gene structure determinants of co-transcriptional control of alternative pre-mRNA splicing. Nucleic Acids Res 2019; 46:10598-10607. [PMID: 30272246 PMCID: PMC6237756 DOI: 10.1093/nar/gky870] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 09/17/2018] [Indexed: 01/22/2023] Open
Abstract
The spliceosome catalyzes the removal of introns from pre-messenger RNA (mRNA) and subsequent pairing of exons with remarkable fidelity. Some exons are known to be skipped or included in the mature mRNA in a cell type- or context-dependent manner (cassette exons), thereby contributing to the diversification of the human proteome. Interestingly, splicing is initiated (and sometimes completed) co-transcriptionally. Here, we develop a kinetic mathematical modeling framework to investigate alternative co-transcriptional splicing (CTS) and, specifically, the control of cassette exons' inclusion. We show that when splicing is co-transcriptional, default splice patterns of exon inclusion are more likely than when splicing is post-transcriptional, and that certain exons are more likely to be regulatable (i.e. cassette exons) than others, based on the exon-intron structure context. For such regulatable exons, transcriptional elongation rates may affect splicing outcomes. Within the CTS paradigm, we examine previously described hypotheses of co-operativity between splice sites of short introns (i.e. 'intron definition') or across short exons (i.e. 'exon definition'), and find that models encoding these faithfully recapitulate observations in the fly and human genomes, respectively.
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Affiliation(s)
- Jeremy Davis-Turak
- San Diego Center for Systems Biology (SDCSB), University of California, San Diego, La Jolla, CA 92093, USA
| | - Tracy L Johnson
- San Diego Center for Systems Biology (SDCSB), University of California, San Diego, La Jolla, CA 92093, USA.,Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA 90095, USA.,Molecular Biology Institute (MBI), University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Alexander Hoffmann
- San Diego Center for Systems Biology (SDCSB), University of California, San Diego, La Jolla, CA 92093, USA.,Molecular Biology Institute (MBI), University of California, Los Angeles, Los Angeles, CA 90095, USA.,Department of Microbiology, Immunology, and Molecular Genetics (MIMG), University of California, Los Angeles, CA 90095, USA.,Institute for Quantitative and Computational Biosciences (QCB) University of California, Los Angeles, Los Angeles, CA 90095, USA
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21
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Turunen TA, Roberts TC, Laitinen P, Väänänen MA, Korhonen P, Malm T, Ylä-Herttuala S, Turunen MP. Changes in nuclear and cytoplasmic microRNA distribution in response to hypoxic stress. Sci Rep 2019; 9:10332. [PMID: 31316122 PMCID: PMC6637125 DOI: 10.1038/s41598-019-46841-1] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 07/05/2019] [Indexed: 02/08/2023] Open
Abstract
MicroRNAs (miRNAs) are small non-coding RNAs that have well-characterized roles in cytoplasmic gene regulation, where they act by binding to mRNA transcripts and inhibiting their translation (i.e. post-transcriptional gene silencing, PTGS). However, miRNAs have also been implicated in transcriptional gene regulation and alternative splicing, events that are restricted to the cell nucleus. Here we performed nuclear-cytoplasmic fractionation in a mouse endothelial cell line and characterized the localization of miRNAs in response to hypoxia using small RNA sequencing. A highly diverse population of abundant miRNA species was detected in the nucleus, of which the majority (56%) was found to be preferentially localized in one compartment or the other. Induction of hypoxia resulted in changes in miRNA levels in both nuclear and cytoplasmic compartments, with the majority of changes being restricted to one location and not the other. Notably, the classical hypoxamiR (miR-210-3p) was highly up-regulated in the nuclear compartment after hypoxic stimulus. These findings reveal a previously unappreciated level of molecular complexity in the physiological response occurring in ischemic tissue. Furthermore, widespread differential miRNA expression in the nucleus strongly suggests that these small RNAs are likely to perform extensive nuclear regulatory functions in the general case.
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Affiliation(s)
- Tiia A Turunen
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Yliopistonranta 1E, 70210, Kuopio, Finland
| | - Thomas C Roberts
- Department of Paediatrics, University of Oxford, South Parks Road, Oxford, OX1 3QX, UK.,Sanford Burnham Prebys Medical Discovery Institute, Development, Aging and Regeneration Program, 10901 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Pia Laitinen
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Yliopistonranta 1E, 70210, Kuopio, Finland
| | - Mari-Anna Väänänen
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Yliopistonranta 1E, 70210, Kuopio, Finland
| | - Paula Korhonen
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Yliopistonranta 1E, 70210, Kuopio, Finland
| | - Tarja Malm
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Yliopistonranta 1E, 70210, Kuopio, Finland
| | - Seppo Ylä-Herttuala
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Yliopistonranta 1E, 70210, Kuopio, Finland.,Heart Center and Gene Therapy Unit, Kuopio University Hospital, PO Box 100, 70029 KUH, Kuopio, Finland
| | - Mikko P Turunen
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Yliopistonranta 1E, 70210, Kuopio, Finland.
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22
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Zuckerman B, Ulitsky I. Predictive models of subcellular localization of long RNAs. RNA (NEW YORK, N.Y.) 2019; 25:557-572. [PMID: 30745363 PMCID: PMC6467007 DOI: 10.1261/rna.068288.118] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2018] [Accepted: 02/07/2019] [Indexed: 05/14/2023]
Abstract
Export to the cytoplasm is a key regulatory junction for both protein-coding mRNAs and long noncoding RNAs (lncRNAs), and cytoplasmic enrichment varies dramatically both within and between those groups. We used a new computational approach and RNA-seq data from human and mouse cells to quantify the genome-wide association between cytoplasmic/nuclear ratios of both gene groups and various factors, including expression levels, splicing efficiency, gene architecture, chromatin marks, and sequence elements. Splicing efficiency emerged as the main predictive factor, explaining up to a third of the variability in localization. Combination with other features allowed predictive models that could explain up to 45% of the variance for protein-coding genes and up to 34% for lncRNAs. Factors associated with localization were similar between lncRNAs and mRNAs with some important differences. Readily accessible features can thus be used to predict RNA localization.
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Affiliation(s)
- Binyamin Zuckerman
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Igor Ulitsky
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot 76100, Israel
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23
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Promoter-proximal pausing mediated by the exon junction complex regulates splicing. Nat Commun 2019; 10:521. [PMID: 30705266 PMCID: PMC6355915 DOI: 10.1038/s41467-019-08381-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 01/04/2019] [Indexed: 02/08/2023] Open
Abstract
Promoter-proximal pausing of RNA polymerase II (Pol II) is a widespread transcriptional regulatory step across metazoans. Here we find that the nuclear exon junction complex (pre-EJC) is a critical and conserved regulator of this process. Depletion of pre-EJC subunits leads to a global decrease in Pol II pausing and to premature entry into elongation. This effect occurs, at least in part, via non-canonical recruitment of pre-EJC components at promoters. Failure to recruit the pre-EJC at promoters results in increased binding of the positive transcription elongation complex (P-TEFb) and in enhanced Pol II release. Notably, restoring pausing is sufficient to rescue exon skipping and the photoreceptor differentiation defect associated with depletion of pre-EJC components in vivo. We propose that the pre-EJC serves as an early transcriptional checkpoint to prevent premature entry into elongation, ensuring proper recruitment of RNA processing components that are necessary for exon definition.
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Kurup JT, Kidder BL. Identification of H4K20me3- and H3K4me3-associated RNAs using CARIP-Seq expands the transcriptional and epigenetic networks of embryonic stem cells. J Biol Chem 2018; 293:15120-15135. [PMID: 30115682 DOI: 10.1074/jbc.ra118.004974] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Indexed: 11/06/2022] Open
Abstract
RNA has been shown to interact with various proteins to regulate chromatin dynamics and gene expression. However, it is unknown whether RNAs associate with epigenetic marks such as post-translational modifications of histones, including histone 4 lysine 20 trimethylation (H4K20me3) or trimethylated histone 3 lysine 4 (H3K4me3), to regulate chromatin and gene expression. Here, we used chromatin-associated RNA immunoprecipitation (CARIP) followed by next-generation sequencing (CARIP-Seq) to survey RNAs associated with H4K20me3- and H3K4me3-marked chromatin on a global scale in embryonic stem (ES) cells. We identified thousands of mRNAs and noncoding RNAs that associate with H4K20me3- and H3K4me3-marked chromatin. H4K20me3- and H3K4me3-interacting RNAs are involved in chromatin organization and modification and RNA processing, whereas H4K20me3-only RNAs are involved in cell motility and differentiation, and H3K4me3-only RNAs are involved in metabolic processes and RNA processing. Expression of H3K4me3-associated RNAs is enriched in ES cells, whereas expression of H4K20me3-associated RNAs is enriched in ES cells and differentiated cells. H4K20me3- and H3K4me3-interacting RNAs originate from genes that co-localize with features of active chromatin, including transcriptional machinery and active promoter regions, and the histone modification H3K36me3 in gene body regions. We also found that H4K20me3 and H3K4me3 are associated with distinct gene features including transcripts of greater length and exon number relative to unoccupied transcripts. H4K20me3- and H3K4me3-marked chromatin is also associated with processed RNAs (exon transcripts) relative to unspliced pre-mRNA and ncRNA transcripts. In summary, our results provide evidence that H4K20me3- and H3K4me3-associated RNAs represent a distinct subnetwork of the ES cell transcriptional repertoire.
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Affiliation(s)
- Jiji T Kurup
- From the Department of Oncology and.,the Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, Michigan 48201
| | - Benjamin L Kidder
- From the Department of Oncology and .,the Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, Michigan 48201
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Cheatham AM, Davis SE, Khatua AK, Popik W. Blocking the 5' splice site of exon 4 by a morpholino oligomer triggers APOL1 protein isoform switch. Sci Rep 2018; 8:8739. [PMID: 29880816 PMCID: PMC5992166 DOI: 10.1038/s41598-018-27104-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 05/21/2018] [Indexed: 12/16/2022] Open
Abstract
APOL1 risk alleles G1 or G2 are associated with a kidney disease phenotype exclusively in people of recent African ancestry. Here we show that exon 4 encoding a part of the APOL1 signal peptide is constitutively spliced in major APOL1 transcripts expressed in kidney glomerular and tubular cells. We demonstrate that constitutive splicing of exon 4 results from a suboptimal hnRNP A1 binding motif found in exon 4. Accordingly, a robust binding of hnRNP A1 protein to a consensus hnRNP A1 cis-acting element in exon 4 results in almost complete exclusion of exon 4 from the APOL1 minigene transcripts. Blocking the 5' splice site at the exon 4/intron boundary with a specific antisense morpholino oligonucleotide excludes exon 4 from the splicing pattern of endogenous APOL1 transcripts. These transcripts are fully functional and produce APOL1 protein isoform that is not normally detectable in podocytes. Together with our previous data showing no cytotoxicity of overexpressed APOL1 isoform lacking exon 4, we propose that morpholino-induced APOL1 isoform switch may provide a new tool to identify in vivo molecular mechanism(s) by which risk alleles promote or mediate the kidney disease phenotype.
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Affiliation(s)
- Amber M Cheatham
- Meharry Medical College, Center for AIDS Health Disparities Research, Department of Microbiology and Immunology, 1005 D. B. Todd Blvd, Nashville, TN, 37028, USA
| | - Shamara E Davis
- Meharry Medical College, Center for AIDS Health Disparities Research, Department of Microbiology and Immunology, 1005 D. B. Todd Blvd, Nashville, TN, 37028, USA
| | - Atanu K Khatua
- Meharry Medical College, Center for AIDS Health Disparities Research, Department of Microbiology and Immunology, 1005 D. B. Todd Blvd, Nashville, TN, 37028, USA
| | - Waldemar Popik
- Meharry Medical College, Center for AIDS Health Disparities Research, Department of Microbiology and Immunology, 1005 D. B. Todd Blvd, Nashville, TN, 37028, USA.
- Department of Internal Medicine, 1005 D. B. Todd Blvd, Nashville, TN, 37028, USA.
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Romero-Barrios N, Legascue MF, Benhamed M, Ariel F, Crespi M. Splicing regulation by long noncoding RNAs. Nucleic Acids Res 2018; 46:2169-2184. [PMID: 29425321 PMCID: PMC5861421 DOI: 10.1093/nar/gky095] [Citation(s) in RCA: 192] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 01/05/2018] [Accepted: 02/01/2018] [Indexed: 12/13/2022] Open
Abstract
Massive high-throughput sequencing techniques allowed the identification of thousands of noncoding RNAs (ncRNAs) and a plethora of different mRNA processing events occurring in higher organisms. Long ncRNAs can act directly as long transcripts or can be processed into active small si/miRNAs. They can modulate mRNA cleavage, translational repression or the epigenetic landscape of their target genes. Recently, certain long ncRNAs have been shown to play a crucial role in the regulation of alternative splicing in response to several stimuli or during disease. In this review, we focus on recent discoveries linking gene regulation by alternative splicing and its modulation by long and small ncRNAs.
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Affiliation(s)
- Natali Romero-Barrios
- Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, INRA, Universities Paris-Sud, Evry and Paris-Diderot, Sorbonne Paris-Cite, University of Paris-Saclay, Batiment 630, 91405 Orsay, France
| | - Maria Florencia Legascue
- Instituto de Agrobiotecnología del Litoral, CONICET, Universidad Nacional del Litoral, Colectora Ruta Nacional 168 km 0, 3000 Santa Fe, Argentina
| | - Moussa Benhamed
- Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, INRA, Universities Paris-Sud, Evry and Paris-Diderot, Sorbonne Paris-Cite, University of Paris-Saclay, Batiment 630, 91405 Orsay, France
| | - Federico Ariel
- Instituto de Agrobiotecnología del Litoral, CONICET, Universidad Nacional del Litoral, Colectora Ruta Nacional 168 km 0, 3000 Santa Fe, Argentina
| | - Martin Crespi
- Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, INRA, Universities Paris-Sud, Evry and Paris-Diderot, Sorbonne Paris-Cite, University of Paris-Saclay, Batiment 630, 91405 Orsay, France
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Munkley J, Livermore K, Rajan P, Elliott DJ. RNA splicing and splicing regulator changes in prostate cancer pathology. Hum Genet 2017; 136:1143-1154. [PMID: 28382513 PMCID: PMC5602090 DOI: 10.1007/s00439-017-1792-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 03/29/2017] [Indexed: 11/26/2022]
Abstract
Changes in mRNA splice patterns have been associated with key pathological mechanisms in prostate cancer progression. The androgen receptor (abbreviated AR) transcription factor is a major driver of prostate cancer pathology and activated by androgen steroid hormones. Selection of alternative promoters by the activated AR can critically alter gene function by switching mRNA isoform production, including creating a pro-oncogenic isoform of the normally tumour suppressor gene TSC2. A number of androgen-regulated genes generate alternatively spliced mRNA isoforms, including a prostate-specific splice isoform of ST6GALNAC1 mRNA. ST6GALNAC1 encodes a sialyltransferase that catalyses the synthesis of the cancer-associated sTn antigen important for cell mobility. Genetic rearrangements occurring early in prostate cancer development place ERG oncogene expression under the control of the androgen-regulated TMPRSS2 promoter to hijack cell behaviour. This TMPRSS2-ERG fusion gene shows different patterns of alternative splicing in invasive versus localised prostate cancer. Alternative AR mRNA isoforms play a key role in the generation of prostate cancer drug resistance, by providing a mechanism through which prostate cancer cells can grow in limited serum androgen concentrations. A number of splicing regulator proteins change expression patterns in prostate cancer and may help drive key stages of disease progression. Up-regulation of SRRM4 establishes neuronal splicing patterns in neuroendocrine prostate cancer. The splicing regulators Sam68 and Tra2β increase expression in prostate cancer. The SR protein kinase SRPK1 that modulates the activity of SR proteins is up-regulated in prostate cancer and has already given encouraging results as a potential therapeutic target in mouse models.
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Affiliation(s)
- Jennifer Munkley
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle, NE1 3BZ, England, UK
| | - Karen Livermore
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle, NE1 3BZ, England, UK
| | - Prabhakar Rajan
- Barts Cancer Institute, John Vane Science Centre, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK
| | - David J Elliott
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle, NE1 3BZ, England, UK.
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A saga of cancer epigenetics: linking epigenetics to alternative splicing. Biochem J 2017; 474:885-896. [PMID: 28270561 DOI: 10.1042/bcj20161047] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 12/29/2016] [Accepted: 01/05/2017] [Indexed: 12/14/2022]
Abstract
The discovery of an increasing number of alternative splicing events in the human genome highlighted that ∼94% of genes generate alternatively spliced transcripts that may produce different protein isoforms with diverse functions. It is now well known that several diseases are a direct and indirect consequence of aberrant splicing events in humans. In addition to the conventional mode of alternative splicing regulation by 'cis' RNA-binding sites and 'trans' RNA-binding proteins, recent literature provides enormous evidence for epigenetic regulation of alternative splicing. The epigenetic modifications may regulate alternative splicing by either influencing the transcription elongation rate of RNA polymerase II or by recruiting a specific splicing regulator via different chromatin adaptors. The epigenetic alterations and aberrant alternative splicing are known to be associated with various diseases individually, but this review discusses/highlights the latest literature on the role of epigenetic alterations in the regulation of alternative splicing and thereby cancer progression. This review also points out the need for further studies to understand the interplay between epigenetic modifications and aberrant alternative splicing in cancer progression.
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Detailed molecular characterization of a novel IDS exonic mutation associated with multiple pseudoexon activation. J Mol Med (Berl) 2016; 95:299-309. [PMID: 27837218 DOI: 10.1007/s00109-016-1484-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 10/12/2016] [Accepted: 11/01/2016] [Indexed: 12/21/2022]
Abstract
Mutations affecting splicing underlie the development of many human genetic diseases, but rather rarely through mechanisms of pseudoexon activation. Here, we describe a novel c.1092T>A mutation in the iduronate-2-sulfatase (IDS) gene detected in a patient with significantly decreased IDS activity and a clinical diagnosis of mild mucopolysaccharidosis II form. The mutation created an exonic de novo acceptor splice site and resulted in a complex splicing pattern with multiple pseudoexon activation in the patient's fibroblasts. Using an extensive series of minigene splicing experiments, we showed that the competition itself between the de novo and authentic splice site led to the bypass of the authentic one. This event then resulted in activation of several cryptic acceptor and donor sites in the upstream intron. As this was an unexpected and previously unreported mechanism of aberrant pseudoexon inclusion, we systematically analysed and disproved that the patient's mutation induced any relevant change in surrounding splicing regulatory elements. Interestingly, all pseudoexons included in the mature transcripts overlapped with the IDS alternative terminal exon 7b suggesting that this sequence represents a key element in the IDS pre-mRNA architecture. These findings extend the spectrum of mechanisms enabling pseudoexon activation and underscore the complexity of mutation-induced splicing aberrations. KEY MESSAGE Novel exonic IDS gene mutation leads to a complex splicing pattern. Mutation activates multiple pseudoexons through a previously unreported mechanism. Multiple cryptic splice site (ss) activation results from a bypass of authentic ss. Authentic ss bypass is due to a competition between de novo and authentic ss.
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Song MA, Brasky TM, Marian C, Weng DY, Taslim C, Dumitrescu RG, Llanos AA, Freudenheim JL, Shields PG. Racial differences in genome-wide methylation profiling and gene expression in breast tissues from healthy women. Epigenetics 2016; 10:1177-87. [PMID: 26680018 DOI: 10.1080/15592294.2015.1121362] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
Breast cancer is more common in European Americans (EAs) than in African Americans (AAs) but mortality from breast cancer is higher among AAs. While there are racial differences in DNA methylation and gene expression in breast tumors, little is known whether such racial differences exist in breast tissues of healthy women. Genome-wide DNA methylation and gene expression profiling was performed in histologically normal breast tissues of healthy women. Linear regression models were used to identify differentially-methylated CpG sites (CpGs) between EAs (n = 61) and AAs (n = 22). Correlations for methylation and expression were assessed. Biological functions of the differentially-methylated genes were assigned using the Ingenuity Pathway Analysis. Among 485 differentially-methylated CpGs by race, 203 were hypermethylated in EAs, and 282 were hypermethylated in AAs. Promoter-related differentially-methylated CpGs were more frequently hypermethylated in EAs (52%) than AAs (27%) while gene body and intergenic CpGs were more frequently hypermethylated in AAs. The differentially-methylated CpGs were enriched for cancer-associated genes with roles in cell death and survival, cellular development, and cell-to-cell signaling. In a separate analysis for correlation in EAs and AAs, different patterns of correlation were found between EAs and AAs. The correlated genes showed different biological networks between EAs and AAs; networks were connected by Ubiquitin C. To our knowledge, this is the first comprehensive genome-wide study to identify differences in methylation and gene expression between EAs and AAs in breast tissues from healthy women. These findings may provide further insights regarding the contribution of epigenetic differences to racial disparities in breast cancer.
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Affiliation(s)
- Min-Ae Song
- a Comprehensive Cancer Center; The Ohio State University and James Cancer Hospital ; Columbus , Ohio , USA
| | - Theodore M Brasky
- a Comprehensive Cancer Center; The Ohio State University and James Cancer Hospital ; Columbus , Ohio , USA
| | - Catalin Marian
- a Comprehensive Cancer Center; The Ohio State University and James Cancer Hospital ; Columbus , Ohio , USA.,b Biochemistry and Pharmacology Department ; Victor Babes University of Medicine and Pharmacy ; 300041 Timisoara , Romania
| | - Daniel Y Weng
- a Comprehensive Cancer Center; The Ohio State University and James Cancer Hospital ; Columbus , Ohio , USA
| | - Cenny Taslim
- a Comprehensive Cancer Center; The Ohio State University and James Cancer Hospital ; Columbus , Ohio , USA
| | | | - Adana A Llanos
- d Department of Epidemiology ; Rutgers School of Public Health and Rutgers Cancer Institute of New Jersey ; New Brunswick , NJ 08903 , USA
| | - Jo L Freudenheim
- e Department of Epidemiology and Environmental Health; School of Public Health and Health Professions ; University at Buffalo ; Buffalo , NY 14214 , USA
| | - Peter G Shields
- a Comprehensive Cancer Center; The Ohio State University and James Cancer Hospital ; Columbus , Ohio , USA
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31
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Huin V, Deramecourt V, Caparros-Lefebvre D, Maurage CA, Duyckaerts C, Kovari E, Pasquier F, Buée-Scherrer V, Labreuche J, Behal H, Buée L, Dhaenens CM, Sablonnière B. TheMAPTgene is differentially methylated in the progressive supranuclear palsy brain. Mov Disord 2016; 31:1883-1890. [DOI: 10.1002/mds.26820] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 08/31/2016] [Accepted: 09/05/2016] [Indexed: 01/03/2023] Open
Affiliation(s)
- Vincent Huin
- Univ. Lille, Inserm, CHU Lille, UMR-S 1172 - JPArc - Centre de Recherche Jean-Pierre AUBERT Neurosciences et Cancer; Lille France
| | - Vincent Deramecourt
- Univ. Lille, Inserm, CHU Lille, UMR-S 1172 - JPArc - Centre de Recherche Jean-Pierre AUBERT Neurosciences et Cancer; Lille France
| | | | - Claude-Alain Maurage
- Univ. Lille, Inserm, CHU Lille, UMR-S 1172 - JPArc - Centre de Recherche Jean-Pierre AUBERT Neurosciences et Cancer; Lille France
| | - Charles Duyckaerts
- Laboratoire de Neuropathologie Escourolle, AP-HP, Hôpital de la Pitié Salpêtrière; Paris France
| | - Eniko Kovari
- Department of Mental Health and Psychiatry; University Hospitals and University of Geneva; Geneva Switzerland
| | - Florence Pasquier
- Univ. Lille, Inserm, CHU Lille, U1171 - CNR-MAJ, DISTALZ; Lille France
| | - Valérie Buée-Scherrer
- Univ. Lille, Inserm, CHU Lille, UMR-S 1172 - JPArc - Centre de Recherche Jean-Pierre AUBERT Neurosciences et Cancer; Lille France
| | - Julien Labreuche
- Univ. Lille, CHU Lille, EA 2694 - Santé publique : épidémiologie et qualité des soins, Département de Statistiques; Lille France
| | - Hélène Behal
- Univ. Lille, CHU Lille, EA 2694 - Santé publique : épidémiologie et qualité des soins, Département de Statistiques; Lille France
| | - Luc Buée
- Univ. Lille, Inserm, CHU Lille, UMR-S 1172 - JPArc - Centre de Recherche Jean-Pierre AUBERT Neurosciences et Cancer; Lille France
| | - Claire-Marie Dhaenens
- Univ. Lille, Inserm, CHU Lille, UMR-S 1172 - JPArc - Centre de Recherche Jean-Pierre AUBERT Neurosciences et Cancer; Lille France
| | - Bernard Sablonnière
- Univ. Lille, Inserm, CHU Lille, UMR-S 1172 - JPArc - Centre de Recherche Jean-Pierre AUBERT Neurosciences et Cancer; Lille France
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32
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Movassat M, Crabb TL, Busch A, Yao C, Reynolds DJ, Shi Y, Hertel KJ. Coupling between alternative polyadenylation and alternative splicing is limited to terminal introns. RNA Biol 2016; 13:646-55. [PMID: 27245359 DOI: 10.1080/15476286.2016.1191727] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Alternative polyadenylation has been implicated as an important regulator of gene expression. In some cases, alternative polyadenylation is known to couple with alternative splicing to influence last intron removal. However, it is unknown whether alternative polyadenylation events influence alternative splicing decisions at upstream exons. Knockdown of the polyadenylation factors CFIm25 or CstF64 in HeLa cells was used as an approach in identifying alternative polyadenylation and alternative splicing events on a genome-wide scale. Although hundreds of alternative splicing events were found to be differentially spliced in the knockdown of CstF64, genes associated with alternative polyadenylation did not exhibit an increased incidence of alternative splicing. These results demonstrate that the coupling between alternative polyadenylation and alternative splicing is usually limited to defining the last exon. The striking influence of CstF64 knockdown on alternative splicing can be explained through its effects on UTR selection of known splicing regulators such as hnRNP A2/B1, thereby indirectly influencing splice site selection. We conclude that changes in the expression of the polyadenylation factor CstF64 influences alternative splicing through indirect effects.
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Affiliation(s)
- Maliheh Movassat
- a Department of Microbiology and Molecular Genetics , School of Medicine, University of California , Irvine , CA , USA
| | - Tara L Crabb
- b Institute of Molecular Biology (IMB) , Mainz , Germany
| | - Anke Busch
- a Department of Microbiology and Molecular Genetics , School of Medicine, University of California , Irvine , CA , USA.,b Institute of Molecular Biology (IMB) , Mainz , Germany
| | - Chengguo Yao
- a Department of Microbiology and Molecular Genetics , School of Medicine, University of California , Irvine , CA , USA
| | - Derrick J Reynolds
- a Department of Microbiology and Molecular Genetics , School of Medicine, University of California , Irvine , CA , USA
| | - Yongsheng Shi
- a Department of Microbiology and Molecular Genetics , School of Medicine, University of California , Irvine , CA , USA
| | - Klemens J Hertel
- a Department of Microbiology and Molecular Genetics , School of Medicine, University of California , Irvine , CA , USA
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G Hendrickson D, Kelley DR, Tenen D, Bernstein B, Rinn JL. Widespread RNA binding by chromatin-associated proteins. Genome Biol 2016; 17:28. [PMID: 26883116 PMCID: PMC4756407 DOI: 10.1186/s13059-016-0878-3] [Citation(s) in RCA: 172] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 01/12/2016] [Indexed: 01/01/2023] Open
Abstract
Background Recent evidence suggests that RNA interaction can regulate the activity and localization of chromatin-associated proteins. However, it is unknown if these observations are specialized instances for a few key RNAs and chromatin factors in specific contexts, or a general mechanism underlying the establishment of chromatin state and regulation of gene expression. Results Here, we perform formaldehyde RNA immunoprecipitation (fRIP-Seq) to survey the RNA associated with a panel of 24 chromatin regulators and traditional RNA binding proteins. For each protein that reproducibly bound measurable quantities of bulk RNA (90 % of the panel), we detect enrichment for hundreds to thousands of both noncoding and mRNA transcripts. Conclusion For each protein, we find that the enriched sets of RNAs share distinct biochemical, functional, and chromatin properties. Thus, these data provide evidence for widespread specific and relevant RNA association across diverse classes of chromatin-modifying complexes. Electronic supplementary material The online version of this article (doi:10.1186/s13059-016-0878-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- David G Hendrickson
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, 02138, USA. .,Broad Institute of Harvard and MIT, Cambridge, MA, 02142, USA.
| | - David R Kelley
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, 02138, USA. .,Broad Institute of Harvard and MIT, Cambridge, MA, 02142, USA.
| | - Danielle Tenen
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, 02138, USA. .,Broad Institute of Harvard and MIT, Cambridge, MA, 02142, USA.
| | | | - John L Rinn
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, 02138, USA. .,Broad Institute of Harvard and MIT, Cambridge, MA, 02142, USA. .,Beth Israel Deaconess Medical Center, Boston, MA, 02215, USA.
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Bovine Herpes Virus 1 Major Immediate Early Transcription Unit 1 (IETU-1) Uses Alternative Promoters to Transcribe BICP0 and BICP4 Transcripts. Curr Microbiol 2015; 72:420-5. [DOI: 10.1007/s00284-015-0961-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 10/30/2015] [Indexed: 10/22/2022]
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Warns JA, Davie JR, Dhasarathy A. Connecting the dots: chromatin and alternative splicing in EMT. Biochem Cell Biol 2015; 94:12-25. [PMID: 26291837 DOI: 10.1139/bcb-2015-0053] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Nature has devised sophisticated cellular machinery to process mRNA transcripts produced by RNA Polymerase II, removing intronic regions and connecting exons together, to produce mature RNAs. This process, known as splicing, is very closely linked to transcription. Alternative splicing, or the ability to produce different combinations of exons that are spliced together from the same genomic template, is a fundamental means of regulating protein complexity. Similar to transcription, both constitutive and alternative splicing can be regulated by chromatin and its associated factors in response to various signal transduction pathways activated by external stimuli. This regulation can vary between different cell types, and interference with these pathways can lead to changes in splicing, often resulting in aberrant cellular states and disease. The epithelial to mesenchymal transition (EMT), which leads to cancer metastasis, is influenced by alternative splicing events of chromatin remodelers and epigenetic factors such as DNA methylation and non-coding RNAs. In this review, we will discuss the role of epigenetic factors including chromatin, chromatin remodelers, DNA methyltransferases, and microRNAs in the context of alternative splicing, and discuss their potential involvement in alternative splicing during the EMT process.
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Affiliation(s)
- Jessica A Warns
- a Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, 501 N. Columbia Road Stop 9061, Grand Forks, ND 58202-9061, USA
| | - James R Davie
- b Children's Hospital Research Institute of Manitoba, John Buhler Research Centre, Winnipeg, Manitoba R3E 3P4, Canada
| | - Archana Dhasarathy
- a Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, 501 N. Columbia Road Stop 9061, Grand Forks, ND 58202-9061, USA
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Baerwald MR, Meek MH, Stephens MR, Nagarajan RP, Goodbla AM, Tomalty KMH, Thorgaard GH, May B, Nichols KM. Migration-related phenotypic divergence is associated with epigenetic modifications in rainbow trout. Mol Ecol 2015; 25:1785-1800. [PMID: 25958780 DOI: 10.1111/mec.13231] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 04/30/2015] [Accepted: 05/01/2015] [Indexed: 12/11/2022]
Abstract
Migration is essential for the reproduction and survival of many animals, yet little is understood about its underlying molecular mechanisms. We used the salmonid Oncorhynchus mykiss to gain mechanistic insight into smoltification, which is a morphological, physiological and behavioural transition undertaken by juveniles in preparation for seaward migration. O. mykiss is experimentally tractable and displays intra- and interpopulation variation in migration propensity. Migratory individuals can produce nonmigratory progeny and vice versa, indicating a high degree of phenotypic plasticity. One potential way that phenotypic plasticity might be linked to variation in migration-related life history tactics is through epigenetic regulation of gene expression. To explore this, we quantitatively measured genome-scale DNA methylation in fin tissue using reduced representation bisulphite sequencing of F2 siblings produced from a cross between steelhead (migratory) and rainbow trout (nonmigratory) lines. We identified 57 differentially methylated regions (DMRs) between smolt and resident O. mykiss juveniles. DMRs were high in magnitude, with up to 62% differential methylation between life history types, and over half of the gene-associated DMRs were in transcriptional regulatory regions. Many of the DMRs encode proteins with activity relevant to migration-related transitions (e.g. circadian rhythm pathway, nervous system development, protein kinase activity). This study provides the first evidence of a relationship between epigenetic variation and life history divergence associated with migration-related traits in any species.
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Affiliation(s)
- Melinda R Baerwald
- Department of Animal Science, University of California - Davis, Davis, CA, 95616
| | - Mariah H Meek
- Department of Animal Science, University of California - Davis, Davis, CA, 95616
| | - Molly R Stephens
- School of Natural Sciences, University of California - Merced, Merced, CA, 95343
| | - Raman P Nagarajan
- GlaxoSmithKline, Cancer Epigenetics Discovery Performance Unit, Collegeville, PA 19426
| | - Alisha M Goodbla
- Department of Animal Science, University of California - Davis, Davis, CA, 95616
| | | | - Gary H Thorgaard
- School of Biological Sciences and Center for Reproductive Biology, Washington State University, Pullman, WA, 99164
| | - Bernie May
- Department of Animal Science, University of California - Davis, Davis, CA, 95616
| | - Krista M Nichols
- Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2725 Montlake Blvd E, Seattle, WA 98112
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Cui H, Dhroso A, Johnson N, Korkin D. The variation game: Cracking complex genetic disorders with NGS and omics data. Methods 2015; 79-80:18-31. [PMID: 25944472 DOI: 10.1016/j.ymeth.2015.04.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Revised: 03/27/2015] [Accepted: 04/17/2015] [Indexed: 12/14/2022] Open
Abstract
Tremendous advances in Next Generation Sequencing (NGS) and high-throughput omics methods have brought us one step closer towards mechanistic understanding of the complex disease at the molecular level. In this review, we discuss four basic regulatory mechanisms implicated in complex genetic diseases, such as cancer, neurological disorders, heart disease, diabetes, and many others. The mechanisms, including genetic variations, copy-number variations, posttranscriptional variations, and epigenetic variations, can be detected using a variety of NGS methods. We propose that malfunctions detected in these mechanisms are not necessarily independent, since these malfunctions are often found associated with the same disease and targeting the same gene, group of genes, or functional pathway. As an example, we discuss possible rewiring effects of the cancer-associated genetic, structural, and posttranscriptional variations on the protein-protein interaction (PPI) network centered around P53 protein. The review highlights multi-layered complexity of common genetic disorders and suggests that integration of NGS and omics data is a critical step in developing new computational methods capable of deciphering this complexity.
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Affiliation(s)
- Hongzhu Cui
- Department of Computer Science, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, United States
| | - Andi Dhroso
- Department of Computer Science, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, United States
| | - Nathan Johnson
- Department of Computer Science, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, United States
| | - Dmitry Korkin
- Department of Computer Science, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, United States; Bioinformatics and Computational Biology Program, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, United States
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Nxf1 natural variant E610G is a semi-dominant suppressor of IAP-induced RNA processing defects. PLoS Genet 2015; 11:e1005123. [PMID: 25835743 PMCID: PMC4383553 DOI: 10.1371/journal.pgen.1005123] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 03/03/2015] [Indexed: 12/13/2022] Open
Abstract
Endogenous retroviruses and retrotransposons contribute functional genetic variation in animal genomes. In mice, Intracisternal A Particles (IAPs) are a frequent source of both new mutations and polymorphism across laboratory strains. Intronic IAPs can induce alternative RNA processing choices, including alternative splicing. We previously showed IAP I∆1 subfamily insertional mutations are suppressed by a wild-derived allele of the major mRNA export factor, Nxf1. Here we show that a wider diversity of IAP insertions present in the mouse reference sequence induce insertion-dependent alternative processing that is suppressed by Nxf1CAST alleles. These insertions typically show more modest gene expression changes than de novo mutations, suggesting selection or attenuation. Genome-wide splicing-sensitive microarrays and gene-focused assays confirm specificity of Nxf1 genetic modifier activity for IAP insertion alleles. Strikingly, CRISPR/Cas9-mediated genome editing demonstrates that a single amino acid substitution in Nxf1, E610G, is sufficient to recreate a quantitative genetic modifier in a co-isogenic background.
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Kfir N, Lev-Maor G, Glaich O, Alajem A, Datta A, Sze S, Meshorer E, Ast G. SF3B1 Association with Chromatin Determines Splicing Outcomes. Cell Rep 2015; 11:618-29. [DOI: 10.1016/j.celrep.2015.03.048] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2014] [Revised: 02/25/2015] [Accepted: 03/22/2015] [Indexed: 01/08/2023] Open
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Kaer K, Speek M. Intronic retroelements: Not just "speed bumps" for RNA polymerase II. Mob Genet Elements 2014; 2:154-157. [PMID: 23061024 PMCID: PMC3463474 DOI: 10.4161/mge.20774] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Two well-known retroelements, L1 and Alu, comprise about one third of the human genome and are nearly equally distributed between the intergenic and intragenic regions. They carry different regulatory elements and contribute structurally and functionally to the expression of our genes. Recent data also suggest that hundreds of intronic L1s and Alus interfere with the transcription of human genes by inducing intron retention, forcing exonization and cryptic polyadenylation. These novel features can be explained with the RNA polymerase kinetic model and suggest that intronic L1s and Alus are not just "speed bumps" in regulation of RNA polymerase traffic. Here we discuss the complexity of the regulation of gene transcription imposed by intronic retroelements and predict that in addition to transcriptional activity, transcription factor binding and nucleosomal occupancy play a significant role in the transcriptional interference effects of the host genes.
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Affiliation(s)
- Kristel Kaer
- Department of Gene Technology; Tallinn University of Technology; Tallinn, Estonia
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41
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Roberts TC. The MicroRNA Biology of the Mammalian Nucleus. MOLECULAR THERAPY. NUCLEIC ACIDS 2014; 3:e188. [PMID: 25137140 PMCID: PMC4221600 DOI: 10.1038/mtna.2014.40] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 07/08/2014] [Indexed: 12/13/2022]
Abstract
MicroRNAs (miRNAs) are a class of genome-encoded small RNAs that are primarily considered to be post-transcriptional negative regulators of gene expression acting in the cytoplasm. Over a decade of research has focused on this canonical paradigm of miRNA function, with many success stories. Indeed, miRNAs have been identified that act as master regulators of a myriad of cellular processes, and many miRNAs are promising therapeutic targets or disease biomarkers. However, it is becoming increasingly apparent that the canonical view of miRNA function is incomplete. Several lines of evidence now point to additional functions for miRNAs in the nucleus of the mammalian cell. The majority of cellular miRNAs are present in both the nucleus and the cytoplasm, and certain miRNAs show specific nuclear enrichment. Additionally, some miRNAs colocalize with sub-nuclear structures such as the nucleolus and chromatin. Multiple components of the miRNA processing machinery are present in the nuclear compartment and are shuttled back and forth across the nuclear envelope. In the nucleus, miRNAs act to regulate the stability of nuclear transcripts, induce epigenetic alterations that either silence or activate transcription at specific gene promoters, and modulate cotranscriptional alternative splicing events. Nuclear miRNA-directed gene regulation constitutes a departure from the prevailing view of miRNA function and as such, warrants detailed further investigation.
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Affiliation(s)
- Thomas C Roberts
- 1] Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California, USA [2] Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
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Bekdash R, Zhang C, Sarkar D. Fetal alcohol programming of hypothalamic proopiomelanocortin system by epigenetic mechanisms and later life vulnerability to stress. Alcohol Clin Exp Res 2014; 38:2323-30. [PMID: 25069392 DOI: 10.1111/acer.12497] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 05/24/2014] [Indexed: 01/01/2023]
Abstract
Hypothalamic proopiomelanocortin (POMC) neurons, one of the major regulators of the hypothalamic-pituitary-adrenal (HPA) axis, immune functions, and energy homeostasis, are vulnerable to the adverse effects of fetal alcohol exposure (FAE). These effects are manifested in POMC neurons by a decrease in Pomc gene expression, a decrement in the levels of its derived peptide β-endorphin and a dysregulation of the stress response in the adult offspring. The HPA axis is a major neuroendocrine system with pivotal physiological functions and mode of regulation. This system has been shown to be perturbed by prenatal alcohol exposure. It has been demonstrated that the perturbation of the HPA axis by FAE is long-lasting and is linked to molecular, neurophysiological, and behavioral changes in exposed individuals. Recently, we showed that the dysregulation of the POMC system function by FAE is induced by epigenetic mechanisms such as hypermethylation of Pomc gene promoter and an alteration in histone marks in POMC neurons. This developmental programming of the POMC system by FAE altered the transcriptome in POMC neurons and induced a hyperresponse to stress in adulthood. These long-lasting epigenetic changes influenced subsequent generations via the male germline. We also demonstrated that the epigenetic programming of the POMC system by FAE was reversed in adulthood with the application of the inhibitors of DNA methylation or histone modifications. Thus, prenatal environmental influences, such as alcohol exposure, could epigenetically modulate POMC neuronal circuits and function to shape adult behavioral patterns. Identifying specific epigenetic factors in hypothalamic POMC neurons that are modulated by fetal alcohol and target Pomc gene could be potentially useful for the development of new therapeutic approaches to treat stress-related diseases in patients with fetal alcohol spectrum disorders.
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Affiliation(s)
- Rola Bekdash
- Endocrinology Program, Department of Animal Sciences, Rutgers, The State University of New Jersey, New Brunswick, New Jersey; Neuroscience Graduate Program, The State University of New Jersey, New Brunswick, New Jersey
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Suzuki MG, Ito H, Aoki F. Effects of RNAi-mediated knockdown of histone methyltransferases on the sex-specific mRNA expression of Imp in the silkworm Bombyx mori. Int J Mol Sci 2014; 15:6772-96. [PMID: 24758924 PMCID: PMC4013661 DOI: 10.3390/ijms15046772] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 03/25/2014] [Accepted: 04/10/2014] [Indexed: 12/11/2022] Open
Abstract
Sexual differentiation in Bombyx mori is controlled by sex-specific splicing of Bmdsx, which results in the omission of exons 3 and 4 in a male-specific manner. In B. mori, insulin-like growth factor II mRNA-binding protein (Imp) is a male-specific factor involved in male-specific splicing of Bmdsx. Male-specific Imp mRNA results from the male-specific inclusion of exon 8. To verify the link between histone methylation and alternative RNA processing in Imp, we examined the effects of RNAi-mediated knockdown of several histone methyltransferases on the sex-specific mRNA expression of Imp. As a result, male-specific expression of Imp mRNA was completely abolished when expression of the H3K79 methyltransferase DOT1L was repressed to <10% of that in control males. Chromatin immunoprecipitation-quantitative PCR analysis revealed a higher distribution of H3K79me2 in normal males than in normal females across Imp. RNA polymerase II (RNAP II) processivity assays indicated that RNAi knockdown of DOT1L in males caused a twofold decrease in RNAP II processivity compared to that in control males, with almost equivalent levels to those observed in normal females. Inhibition of RNAP II-mediated elongation in male cells repressed the male-specific splicing of Imp. Our data suggest the possibility that H3K79me2 accumulation along Imp is associated with the male-specific alternative processing of Imp mRNA that results from increased RNAP II processivity.
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Affiliation(s)
- Masataka G Suzuki
- Division of Biological Sciences, Department of Integrated Biosciences, Graduate School of Frontier Sciences, the University of Tokyo, 302 Bioscience-Bldg, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
| | - Haruka Ito
- Division of Biological Sciences, Department of Integrated Biosciences, Graduate School of Frontier Sciences, the University of Tokyo, 302 Bioscience-Bldg, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
| | - Fugaku Aoki
- Division of Biological Sciences, Department of Integrated Biosciences, Graduate School of Frontier Sciences, the University of Tokyo, 302 Bioscience-Bldg, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
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Ashton-Beaucage D, Udell CM, Gendron P, Sahmi M, Lefrançois M, Baril C, Guenier AS, Duchaine J, Lamarre D, Lemieux S, Therrien M. A functional screen reveals an extensive layer of transcriptional and splicing control underlying RAS/MAPK signaling in Drosophila. PLoS Biol 2014; 12:e1001809. [PMID: 24643257 PMCID: PMC3958334 DOI: 10.1371/journal.pbio.1001809] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Accepted: 02/05/2014] [Indexed: 12/11/2022] Open
Abstract
A global RNAi screening approach in Drosophila cells identifies a large group of transcription and splicing factors that modulate RAS/MAPK signaling by altering the expression of MAPK. The small GTPase RAS is among the most prevalent oncogenes. The evolutionarily conserved RAF-MEK-MAPK module that lies downstream of RAS is one of the main conduits through which RAS transmits proliferative signals in normal and cancer cells. Genetic and biochemical studies conducted over the last two decades uncovered a small set of factors regulating RAS/MAPK signaling. Interestingly, most of these were found to control RAF activation, thus suggesting a central regulatory role for this event. Whether additional factors are required at this level or further downstream remains an open question. To obtain a comprehensive view of the elements functionally linked to the RAS/MAPK cascade, we used a quantitative assay in Drosophila S2 cells to conduct a genome-wide RNAi screen for factors impacting RAS-mediated MAPK activation. The screen led to the identification of 101 validated hits, including most of the previously known factors associated to this pathway. Epistasis experiments were then carried out on individual candidates to determine their position relative to core pathway components. While this revealed several new factors acting at different steps along the pathway—including a new protein complex modulating RAF activation—we found that most hits unexpectedly work downstream of MEK and specifically influence MAPK expression. These hits mainly consist of constitutive splicing factors and thereby suggest that splicing plays a specific role in establishing MAPK levels. We further characterized two representative members of this group and surprisingly found that they act by regulating mapk alternative splicing. This study provides an unprecedented assessment of the factors modulating RAS/MAPK signaling in Drosophila. In addition, it suggests that pathway output does not solely rely on classical signaling events, such as those controlling RAF activation, but also on the regulation of MAPK levels. Finally, it indicates that core splicing components can also specifically impact alternative splicing. The RAS/MAPK pathway is a cornerstone of the cell proliferation signaling apparatus. It has a notable involvement in cancer as mutations in the components of the pathway are associated with aberrant proliferation. Previous work has focused predominantly on post-translational regulation of RAS/MAPK signaling such that a large and intricate network of factors is now known to act on core pathway components. However, regulation at the pre-translational level has not been examined nearly as extensively and is comparatively poorly understood. In this study, we used an unbiased and global screening approach to survey the Drosophila genome—using Drosophila cultured cells—for novel regulators of this pathway. Surprisingly, a majority of our hits were associated to either transcription or mRNA splicing. We used a series of secondary screening assays to determine which part of the RAS/MAPK pathway these candidates target. We found that these factors were not equally distributed along the pathway, but rather converged predominantly on mapk mRNA expression and processing. Our findings raise the intriguing possibility that regulation of mapk transcript production is a key step for a diverse set of regulatory inputs, and may play an important part in RAS/MAPK signaling dynamics.
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Affiliation(s)
- Dariel Ashton-Beaucage
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Québec, Canada
| | - Christian M. Udell
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Québec, Canada
| | - Patrick Gendron
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Québec, Canada
| | - Malha Sahmi
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Québec, Canada
| | - Martin Lefrançois
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Québec, Canada
| | - Caroline Baril
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Québec, Canada
| | - Anne-Sophie Guenier
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Québec, Canada
| | - Jean Duchaine
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Québec, Canada
| | - Daniel Lamarre
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Québec, Canada
- Département de médecine, Université de Montréal, Montréal, Québec, Canada
| | - Sébastien Lemieux
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Québec, Canada
- Département d'informatique et de recherche opérationnelle, Université de Montréal, Montréal, Québec, Canada
| | - Marc Therrien
- Institute for Research in Immunology and Cancer, Laboratory of Intracellular Signaling, Université de Montréal, Montréal, Québec, Canada
- Département de pathologie et de biologie cellulaire, Université de Montréal, Montréal, Québec, Canada
- * E-mail:
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45
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Yu S, Waldholm J, Böhm S, Visa N. Brahma regulates a specific trans-splicing event at the mod(mdg4) locus of Drosophila melanogaster. RNA Biol 2014; 11:134-45. [PMID: 24526065 DOI: 10.4161/rna.27866] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The mod(mdg4) locus of Drosophila melanogaster contains several transcription units encoded on both DNA strands. The mod(mdg4) pre-mRNAs are alternatively spliced, and a very significant fraction of the mature mod(mdg4) mRNAs are formed by trans-splicing. We have studied the transcripts derived from one of the anti-sense regions within the mod(mdg4) locus in order to shed light on the expression of this complex locus. We have characterized the expression of anti-sense mod(mdg4) transcripts in S2 cells, mapped their transcription start sites and cleavage sites, identified and quantified alternatively spliced transcripts, and obtained insight into the regulation of the mod(mdg4) trans-splicing. In a previous study, we had shown that the alternative splicing of some mod(mdg4) transcripts was regulated by Brahma (BRM), the ATPase subunit of the SWI/SNF chromatin-remodeling complex. Here we show, using RNA interference and overexpression of recombinant BRM proteins, that the levels of BRM affect specifically the abundance of a trans-spliced mod(mdg4) mRNA isoform in both S2 cells and larvae. This specific effect on trans-splicing is accompanied by a local increase in the density of RNA polymerase II and by a change in the phosphorylation state of the C-terminal domain of the large subunit of RNA polymerase II. Interestingly, the regulation of the mod(mdg4) splicing by BRM is independent of the ATPase activity of BRM, which suggests that the mechanism by which BRM modulates trans-splicing is independent of its chromatin-remodeling activity.
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Affiliation(s)
- Simei Yu
- Department of Molecular Biosciences; The Wenner-Gren Institute; Stockholm University; Stockholm, Sweden
| | - Johan Waldholm
- Department of Molecular Biosciences; The Wenner-Gren Institute; Stockholm University; Stockholm, Sweden
| | - Stefanie Böhm
- Department of Molecular Biosciences; The Wenner-Gren Institute; Stockholm University; Stockholm, Sweden
| | - Neus Visa
- Department of Molecular Biosciences; The Wenner-Gren Institute; Stockholm University; Stockholm, Sweden
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Zaghlool A, Ameur A, Cavelier L, Feuk L. Splicing in the human brain. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2014; 116:95-125. [PMID: 25172473 DOI: 10.1016/b978-0-12-801105-8.00005-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
It has become increasingly clear over the past decade that RNA has important functions in human cells beyond its role as an intermediate translator of DNA to protein. It is now known that RNA plays highly specific roles in pathways involved in regulatory, structural, and catalytic functions. The complexity of RNA production and regulation has become evident with the advent of high-throughput methods to study the transcriptome. Deep sequencing has revealed an enormous diversity of RNA types and transcript isoforms in human cells. The transcriptome of the human brain is particularly interesting as it contains more expressed genes than other tissues and also displays an extreme diversity of transcript isoforms, indicating that highly complex regulatory pathways are present in the brain. Several of these regulatory proteins are now identified, including RNA-binding proteins that are neuron specific. RNA-binding proteins also play important roles in regulating the splicing process and the temporal and spatial isoform production. While significant progress has been made in understanding the human transcriptome, many questions still remain regarding the basic mechanisms of splicing and subcellular localization of RNA. A long-standing question is to what extent the splicing of pre-mRNA is cotranscriptional and posttranscriptional, respectively. Recent data, including studies of the human brain, indicate that splicing is primarily cotranscriptional in human cells. This chapter describes the current understanding of splicing and splicing regulation in the human brain and discusses the recent global sequence-based analyses of transcription and splicing.
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Affiliation(s)
- Ammar Zaghlool
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden; Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Adam Ameur
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden; Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Lucia Cavelier
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden; Uppsala University Hospital, Uppsala, Sweden
| | - Lars Feuk
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden; Science for Life Laboratory, Uppsala University, Uppsala, Sweden.
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47
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Schor IE, Fiszbein A, Petrillo E, Kornblihtt AR. Intragenic epigenetic changes modulate NCAM alternative splicing in neuronal differentiation. EMBO J 2013; 32:2264-74. [PMID: 23892457 DOI: 10.1038/emboj.2013.167] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 06/28/2013] [Indexed: 12/19/2022] Open
Abstract
Alternative splicing contributes to cell type-specific transcriptomes. Here, we show that changes in intragenic chromatin marks affect NCAM (neural cell adhesion molecule) exon 18 (E18) alternative splicing during neuronal differentiation. An increase in the repressive marks H3K9me2 and H3K27me3 along the gene body correlated with inhibition of polymerase II elongation in the E18 region, but without significantly affecting total mRNA levels. Treatment with the general DNA methylation inhibitor 5-azacytidine and BIX 01294, a specific inhibitor of H3K9 dimethylation, inhibited the differentiation-induced E18 inclusion, pointing to a role for repressive marks in sustaining NCAM splicing patterns typical of mature neurons. We demonstrate that intragenic deployment of repressive chromatin marks, induced by intronic small interfering RNAs targeting NCAM intron 18, promotes E18 inclusion in undifferentiated N2a cells, confirming the chromatin changes observed upon differentiation to be sufficient to induce alternative splicing. Combined with previous evidence that neuronal depolarization causes H3K9 acetylation and subsequent E18 skipping, our results show how two alternative epigenetic marks regulate NCAM alternative splicing and E18 levels in different cellular contexts.
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Affiliation(s)
- Ignacio E Schor
- Laboratorio de Fisiología y Biología Molecular, Departamento de Fisiología, Biología Molecular y Celular, IFIBYNE-UBA-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
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Martinez NM, Lynch KW. Control of alternative splicing in immune responses: many regulators, many predictions, much still to learn. Immunol Rev 2013; 253:216-36. [PMID: 23550649 PMCID: PMC3621013 DOI: 10.1111/imr.12047] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Most mammalian pre-mRNAs are alternatively spliced in a manner that alters the resulting open reading frame. Consequently, alternative pre-mRNA splicing provides an important RNA-based layer of protein regulation and cellular function. The ubiquitous nature of alternative splicing coupled with the advent of technologies that allow global interrogation of the transcriptome have led to an increasing awareness of the possibility that widespread changes in splicing patterns contribute to lymphocyte function during an immune response. Indeed, a few notable examples of alternative splicing have clearly been demonstrated to regulate T-cell responses to antigen. Moreover, several proteins key to the regulation of splicing in T cells have recently been identified. However, much remains to be done to truly identify the spectrum of genes that are regulated at the level of splicing in immune cells and to determine how many of these are controlled by currently known factors and pathways versus unknown mechanisms. Here, we describe the proteins, pathways, and mechanisms that have been shown to regulate alternative splicing in human T cells and discuss what is and is not known about the genes regulated by such factors. Finally, we highlight unifying themes with regards to the mechanisms and consequences of alternative splicing in the adaptive immune system and give our view of important directions for future studies.
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Affiliation(s)
- Nicole M Martinez
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104-6059, USA
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49
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Kwak H, Fuda NJ, Core LJ, Lis JT. Precise maps of RNA polymerase reveal how promoters direct initiation and pausing. Science 2013; 339:950-3. [PMID: 23430654 DOI: 10.1126/science.1229386] [Citation(s) in RCA: 539] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Transcription regulation occurs frequently through promoter-associated pausing of RNA polymerase II (Pol II). We developed a precision nuclear run-on and sequencing (PRO-seq) assay to map the genome-wide distribution of transcriptionally engaged Pol II at base pair resolution. Pol II accumulates immediately downstream of promoters, at intron-exon junctions that are efficiently used for splicing, and over 3' polyadenylation sites. Focused analyses of promoters reveal that pausing is not fixed relative to initiation sites, nor is it specified directly by the position of a particular core promoter element or the first nucleosome. Core promoter elements function beyond initiation, and when optimally positioned they act collectively to dictate the position and strength of pausing. This "complex interaction" model was tested with insertional mutagenesis of the Drosophila Hsp70 core promoter.
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Affiliation(s)
- Hojoong Kwak
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
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50
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Jordaan G, Liao W, Sharma S. E-cadherin gene re-expression in chronic lymphocytic leukemia cells by HDAC inhibitors. BMC Cancer 2013; 13:88. [PMID: 23432814 PMCID: PMC3586366 DOI: 10.1186/1471-2407-13-88] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 02/20/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The tumor suppressor gene E-cadherin gene is frequently silenced in chronic lymphocytic leukemia (CLL) cells and results in wnt-pathway activation. We analyzed the role of histone epigenetic modifications in E-cadherin gene silencing. METHODS CLL specimens were treated with histone deacetylase inhibitor (HDACi) MS-275 and analyzed for E-cadherin expression with western blot and RT-PCR analysis. The downstream effects of HDACi treated leukemic cells were studied by analyzing the effect on wnt-pathway signaling. HDACi induced alterations in E-cadherin splicing were investigated by transcript specific real time PCR analysis. RESULTS Treatment of CLL specimens with histone deacetylase inhibitors (HDACi) treatment resulted in an increase of the E-cadherin RNA transcript (5 to 119 fold increase, n=10) in eight out of ten CLL specimens indicating that this gene is down regulated by histone hypoacetylation in a majority of CLL specimens. The E-cadherin re-expression in CLL specimens was noted by western blot analysis as well. Besides epigenetic silencing another mechanism of E-cadherin inactivation is aberrant exon 11 splicing resulting in an alternatively spliced transcript that lacks exon 11 and is degraded by the non-sense mediated decay (NMD) pathway. Our chromatin immunoprecipitation experiments show that HDACi increased the acetylation of histones H3 and H4 in the E-cadherin promoter region. This also affected the E-cadherin exon 11 splicing pattern as HDACi treated CLL specimens preferentially expressed the correctly spliced transcript and not the exon 11 skipped aberrant transcript. The re-expressed E- cadherin binds to β-catenin with inhibition of the active wnt-beta-catenin pathway in these cells. This resulted in a down regulation of two wnt target genes, LEF and cyclinD1 and the wnt pathway reporter. CONCLUSION The E-cadherin gene is epigenetically modified and hypoacetylated in CLL leukemic cells. Treatment of CLL specimens with HDACi MS-275 activates transcription from this silent gene with expression of more correctly spliced E-cadherin transcripts as compared to the aberrant exon11 skipped transcripts that in turn inhibits the wnt signaling pathway. The data highlights the role of epigenetic modifications in altering gene splicing patterns.
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Affiliation(s)
- Gwen Jordaan
- Division of Hematology-Oncology, Greater Los Angeles VA Healthcare Center, UCLA School of Medicine, 11301 Wilshire Blvd, LA, CA 90073, USA
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