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Da Cunha D, Miro J, Van Goethem C, Notarnicola C, Hugon G, Carnac G, Cossée M, Koenig M, Tuffery-Giraud S. The exon junction complex is required for DMD gene splicing fidelity and myogenic differentiation. Cell Mol Life Sci 2024; 81:150. [PMID: 38512499 PMCID: PMC10957711 DOI: 10.1007/s00018-024-05188-1] [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: 09/10/2023] [Revised: 02/14/2024] [Accepted: 02/28/2024] [Indexed: 03/23/2024]
Abstract
Deposition of the exon junction complex (EJC) upstream of exon-exon junctions helps maintain transcriptome integrity by preventing spurious re-splicing events in already spliced mRNAs. Here we investigate the importance of EJC for the correct splicing of the 2.2-megabase-long human DMD pre-mRNA, which encodes dystrophin, an essential protein involved in cytoskeletal organization and cell signaling. Using targeted RNA-seq, we show that knock-down of the eIF4A3 and Y14 core components of EJC in a human muscle cell line causes an accumulation of mis-splicing events clustered towards the 3' end of the DMD transcript (Dp427m). This deregulation is conserved in the short Dp71 isoform expressed ubiquitously except in adult skeletal muscle and is rescued with wild-type eIF4A3 and Y14 proteins but not with an EJC assembly-defective mutant eIF4A3. MLN51 protein and EJC-associated ASAP/PSAP complexes independently modulate the inclusion of the regulated exons 71 and 78. Our data confirm the protective role of EJC in maintaining splicing fidelity, which in the DMD gene is necessary to preserve the function of the critical C-terminal protein-protein interaction domain of dystrophin present in all tissue-specific isoforms. Given the role of the EJC in maintaining the integrity of dystrophin, we asked whether the EJC could also be involved in the regulation of a mechanism as complex as skeletal muscle differentiation. We found that eIF4A3 knockdown impairs myogenic differentiation by blocking myotube formation. Collectively, our data provide new insights into the functional roles of EJC in human skeletal muscle.
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Affiliation(s)
- Dylan Da Cunha
- PhyMedExp, Univ Montpellier, CNRS, INSERM, Montpellier, France
| | - Julie Miro
- PhyMedExp, Univ Montpellier, CNRS, INSERM, Montpellier, France
| | - Charles Van Goethem
- Laboratoire de Génétique Moléculaire, CHU de Montpellier, Montpellier, France
- Montpellier BioInformatique Pour Le Diagnostic Clinique (MOBIDIC), Plateau de Médecine Moléculaire Et Génomique (PMMG), CHU Montpellier, 34295, Montpellier, France
| | | | - Gérald Hugon
- PhyMedExp, Univ Montpellier, CNRS, INSERM, Montpellier, France
| | - Gilles Carnac
- PhyMedExp, Univ Montpellier, CNRS, INSERM, Montpellier, France
| | - Mireille Cossée
- PhyMedExp, Univ Montpellier, CNRS, INSERM, Montpellier, France
- Laboratoire de Génétique Moléculaire, CHU de Montpellier, Montpellier, France
| | - Michel Koenig
- PhyMedExp, Univ Montpellier, CNRS, INSERM, Montpellier, France
- Laboratoire de Génétique Moléculaire, CHU de Montpellier, Montpellier, France
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2
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Ho CH, Paolantoni C, Bawankar P, Tang Z, Brown S, Roignant J, Treisman JE. An exon junction complex-independent function of Barentsz in neuromuscular synapse growth. EMBO Rep 2022; 23:e53231. [PMID: 34726300 PMCID: PMC8728599 DOI: 10.15252/embr.202153231] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 10/14/2021] [Accepted: 10/15/2021] [Indexed: 01/07/2023] Open
Abstract
The exon junction complex controls the translation, degradation, and localization of spliced mRNAs, and three of its core subunits also play a role in splicing. Here, we show that a fourth subunit, Barentsz, has distinct functions within and separate from the exon junction complex in Drosophila neuromuscular development. The distribution of mitochondria in larval muscles requires Barentsz as well as other exon junction complex subunits and is not rescued by a Barentsz transgene in which residues required for binding to the core subunit eIF4AIII are mutated. In contrast, interactions with the exon junction complex are not required for Barentsz to promote the growth of neuromuscular synapses. We find that the Activin ligand Dawdle shows reduced expression in barentsz mutants and acts downstream of Barentsz to control synapse growth. Both barentsz and dawdle are required in motor neurons, muscles, and glia for normal synapse growth, and exogenous Dawdle can rescue synapse growth in the absence of barentsz. These results identify a biological function for Barentsz that is independent of the exon junction complex.
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Affiliation(s)
- Cheuk Hei Ho
- Skirball Institute for Biomolecular Medicine and Department of Cell BiologyNYU School of MedicineNew YorkNYUSA
| | - Chiara Paolantoni
- Center for Integrative Genomics, Génopode Building, Faculty of Biology and MedicineUniversity of LausanneLausanneSwitzerland
| | - Praveen Bawankar
- Institute of Pharmaceutical and Biomedical SciencesJohannes Gutenberg‐University MainzMainzGermany
| | - Zuojian Tang
- Center for Health Informatics and BioinformaticsNYU Langone Medical CenterNew YorkNYUSA
- Present address:
Computational Biology at Ridgefield US, Global Computational Biology and Digital ScienceBoehringer IngelheimRidgefieldCTUSA
| | - Stuart Brown
- Center for Health Informatics and BioinformaticsNYU Langone Medical CenterNew YorkNYUSA
- Present address:
ExxonMobil Corporate Strategic ResearchAnnandaleNJUSA
| | - Jean‐Yves Roignant
- Center for Integrative Genomics, Génopode Building, Faculty of Biology and MedicineUniversity of LausanneLausanneSwitzerland
- Institute of Pharmaceutical and Biomedical SciencesJohannes Gutenberg‐University MainzMainzGermany
| | - Jessica E Treisman
- Skirball Institute for Biomolecular Medicine and Department of Cell BiologyNYU School of MedicineNew YorkNYUSA
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3
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Wang B, Rong X, Zhou Y, Liu Y, Sun J, Zhao B, Deng B, Lu L, Lu L, Li Y, Zhou J. Eukaryotic initiation factor 4A3 inhibits Wnt/β-catenin signaling and regulates axis formation in zebrafish embryos. Development 2021; 148:261699. [PMID: 33914867 DOI: 10.1242/dev.198101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 03/25/2021] [Indexed: 12/31/2022]
Abstract
A key step in the activation of canonical Wnt signaling is the interaction between β-catenin and Tcf/Lefs that forms the transcription activation complex and facilitates the expression of target genes. Eukaryotic initiation factor 4A3 (EIF4A3) is an ATP-dependent DEAD box-family RNA helicase and acts as a core subunit of the exon junction complex (EJC) to control a series of RNA post-transcriptional processes. In this study, we uncover that EIF4A3 functions as a Wnt inhibitor by interfering with the formation of β-catenin/Tcf transcription activation complex. As Wnt stimulation increases, accumulated β-catenin displaces EIF4A3 from a transcriptional complex with Tcf/Lef, allowing the active complex to facilitate the expression of target genes. In zebrafish embryos, eif4a3 depletion inhibited the development of the dorsal organizer and pattern formation of the anterior neuroectoderm by increasing Wnt/β-catenin signaling. Conversely, overexpression of eif4a3 decreased Wnt/β-catenin signaling and inhibited the formation of the dorsal organizer before gastrulation. Our results reveal previously unreported roles of EIF4A3 in the inhibition of Wnt signaling and the regulation of embryonic development in zebrafish.
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Affiliation(s)
- Bo Wang
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Xiaozhi Rong
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China.,Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266003, China
| | - Yumei Zhou
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Yunzhang Liu
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Jiqin Sun
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Beibei Zhao
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Bei Deng
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Lei Lu
- Model Animal Research Center of Nanjing University and MOE Key Laboratory of Model Animals for Disease Study, 12 Xuefu Road, Pukou High-Tech Zone, Nanjing 210061, China
| | - Ling Lu
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Yun Li
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China.,Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266003, China
| | - Jianfeng Zhou
- Key Laboratory of Marine Drugs (Ocean University of China), Chinese Ministry of Education, and School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China.,Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266003, China
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4
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Gangras P, Gallagher TL, Parthun MA, Yi Z, Patton RD, Tietz KT, Deans NC, Bundschuh R, Amacher SL, Singh G. Zebrafish rbm8a and magoh mutants reveal EJC developmental functions and new 3'UTR intron-containing NMD targets. PLoS Genet 2020; 16:e1008830. [PMID: 32502192 PMCID: PMC7310861 DOI: 10.1371/journal.pgen.1008830] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 06/23/2020] [Accepted: 05/05/2020] [Indexed: 12/11/2022] Open
Abstract
Many post-transcriptional mechanisms operate via mRNA 3'UTRs to regulate protein expression, and such controls are crucial for development. We show that homozygous mutations in two zebrafish exon junction complex (EJC) core genes rbm8a and magoh leads to muscle disorganization, neural cell death, and motor neuron outgrowth defects, as well as dysregulation of mRNAs subjected to nonsense-mediated mRNA decay (NMD) due to translation termination ≥ 50 nts upstream of the last exon-exon junction. Intriguingly, we find that EJC-dependent NMD also regulates a subset of transcripts that contain 3'UTR introns (3'UI) < 50 nts downstream of a stop codon. Some transcripts containing such stop codon-proximal 3'UI are also NMD-sensitive in cultured human cells and mouse embryonic stem cells. We identify 167 genes that contain a conserved proximal 3'UI in zebrafish, mouse and humans. foxo3b is one such proximal 3'UI-containing gene that is upregulated in zebrafish EJC mutant embryos, at both mRNA and protein levels, and loss of foxo3b function in EJC mutant embryos significantly rescues motor axon growth defects. These data are consistent with EJC-dependent NMD regulating foxo3b mRNA to control protein expression during zebrafish development. Our work shows that the EJC is critical for normal zebrafish development and suggests that proximal 3'UIs may serve gene regulatory function in vertebrates.
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Affiliation(s)
- Pooja Gangras
- Department of Molecular Genetics, The Ohio State University, Ohio, United States of America
- Center for RNA Biology, The Ohio State University, Ohio, United States of America
| | - Thomas L. Gallagher
- Department of Molecular Genetics, The Ohio State University, Ohio, United States of America
- Center for RNA Biology, The Ohio State University, Ohio, United States of America
| | - Michael A. Parthun
- Department of Molecular Genetics, The Ohio State University, Ohio, United States of America
- Center for RNA Biology, The Ohio State University, Ohio, United States of America
| | - Zhongxia Yi
- Department of Molecular Genetics, The Ohio State University, Ohio, United States of America
- Center for RNA Biology, The Ohio State University, Ohio, United States of America
| | - Robert D. Patton
- Center for RNA Biology, The Ohio State University, Ohio, United States of America
- Department of Physics, The Ohio State University, Ohio, United States of America
| | - Kiel T. Tietz
- Department of Molecular Genetics, The Ohio State University, Ohio, United States of America
- Center for RNA Biology, The Ohio State University, Ohio, United States of America
| | - Natalie C. Deans
- Department of Molecular Genetics, The Ohio State University, Ohio, United States of America
- Center for RNA Biology, The Ohio State University, Ohio, United States of America
| | - Ralf Bundschuh
- Center for RNA Biology, The Ohio State University, Ohio, United States of America
- Department of Physics, The Ohio State University, Ohio, United States of America
- Department of Chemistry and Biochemistry, The Ohio State University, Ohio, United States of America
- Division of Hematology, Department of Internal Medicine, The Ohio State University, Ohio, United States of America
| | - Sharon L. Amacher
- Department of Molecular Genetics, The Ohio State University, Ohio, United States of America
- Center for RNA Biology, The Ohio State University, Ohio, United States of America
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Ohio, United States of America
- Center for Muscle Health and Neuromuscular Disorders, The Ohio State University and Nationwide Children’s Hospital, Ohio, United States of America
| | - Guramrit Singh
- Department of Molecular Genetics, The Ohio State University, Ohio, United States of America
- Center for RNA Biology, The Ohio State University, Ohio, United States of America
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5
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Large-Scale Profiling of RBP-circRNA Interactions from Public CLIP-Seq Datasets. Genes (Basel) 2020; 11:genes11010054. [PMID: 31947823 PMCID: PMC7016857 DOI: 10.3390/genes11010054] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 12/26/2019] [Accepted: 12/29/2019] [Indexed: 12/14/2022] Open
Abstract
Circular RNAs are a special type of RNA that has recently attracted a lot of research interest in studying its formation and function. RNA binding proteins (RBPs) that bind circRNAs are important in these processes, but have been relatively less studied. CLIP-Seq technology has been invented and applied to profile RBP-RNA interactions on the genome-wide scale. While mRNAs are usually the focus of CLIP-Seq experiments, RBP-circRNA interactions could also be identified through specialized analysis of CLIP-Seq datasets. However, many technical difficulties are involved in this process, such as the usually short read length of CLIP-Seq reads. In this study, we created a pipeline called Clirc specialized for profiling circRNAs in CLIP-Seq data and analyzing the characteristics of RBP-circRNA interactions. In conclusion, to our knowledge, this is one of the first studies to investigate circRNAs and their binding partners through repurposing CLIP-Seq datasets, and we hope our work will become a valuable resource for future studies into the biogenesis and function of circRNAs.
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6
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Girardot M, Bayet E, Maurin J, Fort P, Roux P, Raynaud P. SOX9 has distinct regulatory roles in alternative splicing and transcription. Nucleic Acids Res 2019; 46:9106-9118. [PMID: 29901772 PMCID: PMC6158501 DOI: 10.1093/nar/gky553] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 06/07/2018] [Indexed: 11/30/2022] Open
Abstract
SOX9 is known as a crucial transcription factor for various developmental processes and for tissue homeostasis. We examined here its potential role in alternative splicing by analyzing global splicing changes, using RNA-seq of colon tumor cells. We show that SOX9 knockdown alters the splicing of hundreds of genes without affecting their expression levels, revealing that SOX9 controls distinct splicing and transcriptional programs. SOX9 does not affect splicing patterns through the control of splicing factors expression. We identify mutants that uncouple SOX9 splicing function from its transcriptional activity. We demonstrate that SOX9 binds to RNA and associates with several RNA-binding proteins, including the core exon junction complex component Y14. Half of SOX9 splicing targets are also modulated by Y14 and are no longer regulated by SOX9 upon Y14 depletion. Altogether, our work reveals that SOX9 is a moonlighting protein which modulates either transcription or splicing of distinct sets of targets.
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Affiliation(s)
- Michael Girardot
- IGMM, CNRS, University of Montpellier, 34293 Montpellier CEDEX 5, France
| | - Elsa Bayet
- CRBM, CNRS, University of Montpellier, 34293 Montpellier CEDEX 5, France
| | - Justine Maurin
- CRBM, CNRS, University of Montpellier, 34293 Montpellier CEDEX 5, France
| | - Philippe Fort
- CRBM, CNRS, University of Montpellier, 34293 Montpellier CEDEX 5, France
| | - Pierre Roux
- CRBM, CNRS, University of Montpellier, 34293 Montpellier CEDEX 5, France
| | - Peggy Raynaud
- CRBM, CNRS, University of Montpellier, 34293 Montpellier CEDEX 5, France
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7
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Miller EE, Kobayashi GS, Musso CM, Allen M, Ishiy FAA, de Caires LC, Goulart E, Griesi-Oliveira K, Zechi-Ceide RM, Richieri-Costa A, Bertola DR, Passos-Bueno MR, Silver DL. EIF4A3 deficient human iPSCs and mouse models demonstrate neural crest defects that underlie Richieri-Costa-Pereira syndrome. Hum Mol Genet 2017; 26:2177-2191. [PMID: 28334780 DOI: 10.1093/hmg/ddx078] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 02/28/2017] [Indexed: 11/14/2022] Open
Abstract
Biallelic loss-of-function mutations in the RNA-binding protein EIF4A3 cause Richieri-Costa-Pereira syndrome (RCPS), an autosomal recessive condition mainly characterized by craniofacial and limb malformations. However, the pathogenic cellular mechanisms responsible for this syndrome are entirely unknown. Here, we used two complementary approaches, patient-derived induced pluripotent stem cells (iPSCs) and conditional Eif4a3 mouse models, to demonstrate that defective neural crest cell (NCC) development explains RCPS craniofacial abnormalities. RCPS iNCCs have decreased migratory capacity, a distinct phenotype relative to other craniofacial disorders. Eif4a3 haploinsufficient embryos presented altered mandibular process fusion and micrognathia, thus recapitulating the most penetrant phenotypes of the syndrome. These defects were evident in either ubiquitous or NCC-specific Eif4a3 haploinsufficient animals, demonstrating an autonomous requirement of Eif4a3 in NCCs. Notably, RCPS NCC-derived mesenchymal stem-like cells (nMSCs) showed premature bone differentiation, a phenotype paralleled by premature clavicle ossification in Eif4a3 haploinsufficient embryos. Likewise, nMSCs presented compromised in vitro chondrogenesis, and Meckel's cartilage was underdeveloped in vivo. These findings indicate novel and essential requirements of EIF4A3 for NCC migration and osteochondrogenic differentiation during craniofacial development. Altogether, complementary use of iPSCs and mouse models pinpoint unique cellular mechanisms by which EIF4A3 mutation causes RCPS, and provide a paradigm to study craniofacial disorders.
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Affiliation(s)
- Emily E Miller
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA
| | - Gerson S Kobayashi
- Department of Genetics and Evolutionary Biology, Human Genome and Stem Cell Research Center, Institute of Biosciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Camila M Musso
- Department of Genetics and Evolutionary Biology, Human Genome and Stem Cell Research Center, Institute of Biosciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Miranda Allen
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA
| | - Felipe A A Ishiy
- Department of Genetics and Evolutionary Biology, Human Genome and Stem Cell Research Center, Institute of Biosciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Luiz Carlos de Caires
- Department of Genetics and Evolutionary Biology, Human Genome and Stem Cell Research Center, Institute of Biosciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Ernesto Goulart
- Department of Genetics and Evolutionary Biology, Human Genome and Stem Cell Research Center, Institute of Biosciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Karina Griesi-Oliveira
- Department of Genetics and Evolutionary Biology, Human Genome and Stem Cell Research Center, Institute of Biosciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Roseli M Zechi-Ceide
- Department of Clinical Genetics, Hospital for Rehabilitation of Craniofacial Anomalies (HRCA), University of São Paulo, Bauru, Brazil
| | - Antonio Richieri-Costa
- Department of Clinical Genetics, Hospital for Rehabilitation of Craniofacial Anomalies (HRCA), University of São Paulo, Bauru, Brazil
| | - Debora R Bertola
- Department of Genetics and Evolutionary Biology, Human Genome and Stem Cell Research Center, Institute of Biosciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Maria Rita Passos-Bueno
- Department of Genetics and Evolutionary Biology, Human Genome and Stem Cell Research Center, Institute of Biosciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Debra L Silver
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA.,Department of Neurobiology.,Department of Cell Biology.,Duke Institute for Brain Sciences, Duke University Medical Center, Durham, NC, USA
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8
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Woodward LA, Mabin JW, Gangras P, Singh G. The exon junction complex: a lifelong guardian of mRNA fate. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 8. [PMID: 28008720 DOI: 10.1002/wrna.1411] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 10/27/2016] [Accepted: 11/09/2016] [Indexed: 12/28/2022]
Abstract
During messenger RNA (mRNA) biogenesis and processing in the nucleus, many proteins are imprinted on mRNAs assembling them into messenger ribonucleoproteins (mRNPs). Some of these proteins remain stably bound within mRNPs and have a long-lasting impact on their fate. One of the best-studied examples is the exon junction complex (EJC), a multiprotein complex deposited primarily 24 nucleotides upstream of exon-exon junctions as a consequence of pre-mRNA splicing. The EJC maintains a stable, sequence-independent, hold on the mRNA until its removal during translation in the cytoplasm. Acting as a molecular shepherd, the EJC travels with mRNA across the cellular landscape coupling pre-mRNA splicing to downstream, posttranscriptional processes such as mRNA export, mRNA localization, translation, and nonsense-mediated mRNA decay (NMD). In this review, we discuss our current understanding of the EJC's functions during these processes, and expound its newly discovered functions (e.g., pre-mRNA splicing). Another focal point is the recently unveiled in vivo EJC interactome, which has shed new light on the EJC's location on the spliced RNAs and its intimate relationship with other mRNP components. We summarize new strides being made in connecting the EJC's molecular function with phenotypes, informed by studies of human disorders and model organisms. The progress toward understanding EJC functions has revealed, in its wake, even more questions, which are discussed throughout. WIREs RNA 2017, 8:e1411. doi: 10.1002/wrna.1411 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Lauren A Woodward
- Department of Molecular Genetics, The Ohio State University, Columbus, OH, USA
| | - Justin W Mabin
- Department of Molecular Genetics, The Ohio State University, Columbus, OH, USA
| | - Pooja Gangras
- Department of Molecular Genetics, The Ohio State University, Columbus, OH, USA
| | - Guramrit Singh
- Department of Molecular Genetics, The Ohio State University, Columbus, OH, USA
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9
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Mao H, McMahon JJ, Tsai YH, Wang Z, Silver DL. Haploinsufficiency for Core Exon Junction Complex Components Disrupts Embryonic Neurogenesis and Causes p53-Mediated Microcephaly. PLoS Genet 2016; 12:e1006282. [PMID: 27618312 PMCID: PMC5019403 DOI: 10.1371/journal.pgen.1006282] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 08/08/2016] [Indexed: 01/05/2023] Open
Abstract
The exon junction complex (EJC) is an RNA binding complex comprised of the core components Magoh, Rbm8a, and Eif4a3. Human mutations in EJC components cause neurodevelopmental pathologies. Further, mice heterozygous for either Magoh or Rbm8a exhibit aberrant neurogenesis and microcephaly. Yet despite the requirement of these genes for neurodevelopment, the pathogenic mechanisms linking EJC dysfunction to microcephaly remain poorly understood. Here we employ mouse genetics, transcriptomic and proteomic analyses to demonstrate that haploinsufficiency for each of the 3 core EJC components causes microcephaly via converging regulation of p53 signaling. Using a new conditional allele, we first show that Eif4a3 haploinsufficiency phenocopies aberrant neurogenesis and microcephaly of Magoh and Rbm8a mutant mice. Transcriptomic and proteomic analyses of embryonic brains at the onset of neurogenesis identifies common pathways altered in each of the 3 EJC mutants, including ribosome, proteasome, and p53 signaling components. We further demonstrate all 3 mutants exhibit defective splicing of RNA regulatory proteins, implying an EJC dependent RNA regulatory network that fine-tunes gene expression. Finally, we show that genetic ablation of one downstream pathway, p53, significantly rescues microcephaly of all 3 EJC mutants. This implicates p53 activation as a major node of neurodevelopmental pathogenesis following EJC impairment. Altogether our study reveals new mechanisms to help explain how EJC mutations influence neurogenesis and underlie neurodevelopmental disease.
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Affiliation(s)
- Hanqian Mao
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - John J. McMahon
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Yi-Hsuan Tsai
- Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Zefeng Wang
- Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Debra L. Silver
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina, United States of America
- Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina, United States of America
- Department of Neurobiology, Duke University School of Medicine, Durham, North Carolina, United States of America
- Duke Institute for Brain Sciences, Duke University, Durham, North Carolina, United States of America
- * E-mail:
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10
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Hir HL, Saulière J, Wang Z. The exon junction complex as a node of post-transcriptional networks. Nat Rev Mol Cell Biol 2015; 17:41-54. [DOI: 10.1038/nrm.2015.7] [Citation(s) in RCA: 167] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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11
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Volodarsky M, Lichtig H, Leibson T, Sadaka Y, Kadir R, Perez Y, Liani-Leibson K, Gradstein L, Shaco-Levy R, Shorer Z, Frank D, Birk OS. CDC174, a novel component of the exon junction complex whose mutation underlies a syndrome of hypotonia and psychomotor developmental delay. Hum Mol Genet 2015; 24:6485-91. [PMID: 26358778 DOI: 10.1093/hmg/ddv357] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 09/01/2015] [Indexed: 11/14/2022] Open
Abstract
Siblings of non-consanguineous Jewish-Ethiopian ancestry presented with congenital axial hypotonia, weakness of the abducens nerve, psychomotor developmental delay with brain ventriculomegaly, variable thinning of corpus callosum and cardiac septal defects. Homozygosity mapping identified a single disease-associated locus of 3.5 Mb on chromosome 3. Studies of a Bedouin consanguineous kindred affected with a similar recessive phenotype identified a single disease-associated 18 Mb homozygosity locus encompassing the entire 3.5 Mb locus. Whole exome sequencing demonstrated only two homozygous mutations within a shared identical haplotype of 0.6 Mb, common to both Bedouin and Ethiopian affected individuals, suggesting an ancient common founder. Only one of the mutations segregated as expected in both kindreds and was not found in Bedouin and Jewish-Ethiopian controls: c.1404A>G, p.[*468Trpext*6] in CCDC174. We showed that CCDC174 is ubiquitous, restricted to the cell nucleus and co-localized with EIF4A3. In fact, yeast-two-hybrid assay demonstrated interaction of CCDC174 with EIF4A3, a component of exon junction complex. Knockdown of the CCDC174 ortholog in Xenopus laevis embryos resulted in poor neural fold closure at the neurula stage with later embryonic lethality. Knockdown embryos exhibited a sharp reduction in expression of n-tubulin, a marker for differentiating primary neurons, and of hindbrain markers krox20 and hoxb3. The Xenopus phenotype could be rescued by the human normal, yet not the mutant CCDC174 transcripts. Moreover, overexpression of mutant but not normal CCDC174 in neuroblastoma cells caused rapid apoptosis. In line with the hypotonia phenotype, the CCDC174 mutation caused depletion of RYR1 and marked myopathic changes in skeletal muscle of affected individuals.
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Affiliation(s)
- Michael Volodarsky
- The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev and Faculty of Health Sciences, Ben Gurion University, Beer Sheva 84105, Israel
| | - Hava Lichtig
- Department of Biochemistry, The Rappaport Family Institute for Research in the Medical Sciences, Faculty of Medicine, Technion, Israel Institute of Technology, Haifa 31096, Israel
| | - Tom Leibson
- Department of Pediatrics, Soroka University Medical Center, Ben Gurion University, Beer Sheva 84101, Israel
| | - Yair Sadaka
- Department of Pediatrics, Soroka University Medical Center, Ben Gurion University, Beer Sheva 84101, Israel, Pediatric Neurology Unit, Soroka University Medical Center, Ben Gurion University, Beer Sheva 84101, Israel
| | - Rotem Kadir
- The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev and Faculty of Health Sciences, Ben Gurion University, Beer Sheva 84105, Israel
| | - Yonatan Perez
- The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev and Faculty of Health Sciences, Ben Gurion University, Beer Sheva 84105, Israel
| | - Keren Liani-Leibson
- The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev and Faculty of Health Sciences, Ben Gurion University, Beer Sheva 84105, Israel
| | - Libe Gradstein
- Department of Ophthalmology, Soroka University Medical Center and Clalit Health Services, Ben Gurion University, Beer Sheva 84101, Israel and
| | - Ruthy Shaco-Levy
- Department of Pathology, Soroka University Medical Center, Ben Gurion University, Beer Sheva 84101, Israel
| | - Zamir Shorer
- Department of Pediatrics, Soroka University Medical Center, Ben Gurion University, Beer Sheva 84101, Israel, Pediatric Neurology Unit, Soroka University Medical Center, Ben Gurion University, Beer Sheva 84101, Israel, Zlotowski Center of Neuroscience, Ben-Gurion University of the Negev, Beer Sheva 94105, Israel
| | - Dale Frank
- Department of Biochemistry, The Rappaport Family Institute for Research in the Medical Sciences, Faculty of Medicine, Technion, Israel Institute of Technology, Haifa 31096, Israel
| | - Ohad S Birk
- The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev and Faculty of Health Sciences, Ben Gurion University, Beer Sheva 84105, Israel, Genetics Institute, Soroka University Medical Center, Ben Gurion University, Beer Sheva 84101, Israel,
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Wang Z, Murigneux V, Le Hir H. Transcriptome-wide modulation of splicing by the exon junction complex. Genome Biol 2015; 15:551. [PMID: 25476502 PMCID: PMC4268817 DOI: 10.1186/s13059-014-0551-7] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Indexed: 11/23/2022] Open
Abstract
Background The exon junction complex (EJC) is a dynamic multi-protein complex deposited onto nuclear spliced mRNAs upstream of exon-exon junctions. The four core proteins, eIF4A3, Magoh, Y14 and MLN51, are stably bound to mRNAs during their lifecycle, serving as a binding platform for other nuclear and cytoplasmic proteins. Recent evidence has shown that the EJC is involved in the splicing regulation of some specific events in both Drosophila and mammalian cells. Results Here, we show that knockdown of EJC core proteins causes widespread alternative splicing changes in mammalian cells. These splicing changes are specific to EJC core proteins, as knockdown of eIF4A3, Y14 and MLN51 shows similar splicing changes, and are different from knockdown of other splicing factors. The splicing changes can be rescued by a siRNA-resistant form of eIF4A3, indicating an involvement of EJC core proteins in regulating alternative splicing. Finally, we find that the splicing changes are linked with RNA polymerase II elongation rates. Conclusion Taken together, this study reveals that the coupling between EJC proteins and splicing is broader than previously suspected, and that a possible link exists between mRNP assembly and splice site recognition. Electronic supplementary material The online version of this article (doi:10.1186/s13059-014-0551-7) contains supplementary material, which is available to authorized users.
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Malone CD, Mestdagh C, Akhtar J, Kreim N, Deinhard P, Sachidanandam R, Treisman J, Roignant JY. The exon junction complex controls transposable element activity by ensuring faithful splicing of the piwi transcript. Genes Dev 2014; 28:1786-99. [PMID: 25104425 PMCID: PMC4197963 DOI: 10.1101/gad.245829.114] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The exon junction complex (EJC) is a highly conserved ribonucleoprotein complex that binds RNAs during splicing and remains associated with them following export to the cytoplasm. Malone et al. describe a novel function for the EJC and its splicing subunit, RnpS1, in controlling piwi transcript splicing, where, in the absence of RnpS1, the fourth intron of piwi is retained. RnpS1-dependent removal of this intron requires splicing of the flanking introns. These data demonstrate a novel role for the EJC in regulating piwi intron excision and provide a mechanism for its function during splicing. The exon junction complex (EJC) is a highly conserved ribonucleoprotein complex that binds RNAs during splicing and remains associated with them following export to the cytoplasm. While the role of this complex in mRNA localization, translation, and degradation has been well characterized, its mechanism of action in splicing a subset of Drosophila and human transcripts remains to be elucidated. Here, we describe a novel function for the EJC and its splicing subunit, RnpS1, in preventing transposon accumulation in both Drosophila germline and surrounding somatic follicle cells. This function is mediated specifically through the control of piwi transcript splicing, where, in the absence of RnpS1, the fourth intron of piwi is retained. This intron contains a weak polypyrimidine tract that is sufficient to confer dependence on RnpS1. Finally, we demonstrate that RnpS1-dependent removal of this intron requires splicing of the flanking introns, suggesting a model in which the EJC facilitates the splicing of weak introns following its initial deposition at adjacent exon junctions. These data demonstrate a novel role for the EJC in regulating piwi intron excision and provide a mechanism for its function during splicing.
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Affiliation(s)
- Colin D Malone
- Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, New York, New York 10016, USA; Howard Hughes Medical Institute
| | | | - Junaid Akhtar
- Institute of Molecular Biology (IMB), 55128 Mainz, Germany
| | - Nastasja Kreim
- Institute of Molecular Biology (IMB), 55128 Mainz, Germany
| | - Pia Deinhard
- Institute of Molecular Biology (IMB), 55128 Mainz, Germany
| | - Ravi Sachidanandam
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Jessica Treisman
- Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, New York, New York 10016, USA
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