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Kumar M, Tyagi N, Faruq M. The molecular mechanisms of spinocerebellar ataxias for DNA repeat expansion in disease. Emerg Top Life Sci 2023; 7:289-312. [PMID: 37668011 DOI: 10.1042/etls20230013] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 08/01/2023] [Accepted: 08/16/2023] [Indexed: 09/06/2023]
Abstract
Spinocerebellar ataxias (SCAs) are a heterogenous group of neurodegenerative disorders which commonly inherited in an autosomal dominant manner. They cause muscle incoordination due to degeneration of the cerebellum and other parts of nervous system. Out of all the characterized (>50) SCAs, 14 SCAs are caused due to microsatellite repeat expansion mutations. Repeat expansions can result in toxic protein gain-of-function, protein loss-of-function, and/or RNA gain-of-function effects. The location and the nature of mutation modulate the underlying disease pathophysiology resulting in varying disease manifestations. Potential toxic effects of these mutations likely affect key major cellular processes such as transcriptional regulation, mitochondrial functioning, ion channel dysfunction and synaptic transmission. Involvement of several common pathways suggests interlinked function of genes implicated in the disease pathogenesis. A better understanding of the shared and distinct molecular pathogenic mechanisms in these diseases is required to develop targeted therapeutic tools and interventions for disease management. The prime focus of this review is to elaborate on how expanded 'CAG' repeats contribute to the common modes of neurotoxicity and their possible therapeutic targets in management of such devastating disorders.
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Affiliation(s)
- Manish Kumar
- CSIR-Institute of Genomics and Integrative Biology, Mall Road, Delhi 110007, India
| | - Nishu Tyagi
- CSIR-Institute of Genomics and Integrative Biology, Mall Road, Delhi 110007, India
| | - Mohammed Faruq
- CSIR-Institute of Genomics and Integrative Biology, Mall Road, Delhi 110007, India
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2
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Jung S, Shah S, Han G, Richter JD. FMRP deficiency leads to multifactorial dysregulation of splicing and mislocalization of MBNL1 to the cytoplasm. PLoS Biol 2023; 21:e3002417. [PMID: 38048343 PMCID: PMC10721184 DOI: 10.1371/journal.pbio.3002417] [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: 12/30/2022] [Revised: 12/14/2023] [Accepted: 11/03/2023] [Indexed: 12/06/2023] Open
Abstract
Fragile X syndrome (FXS) is a neurodevelopmental disorder that is often modeled in Fmr1 knockout mice where the RNA-binding protein FMRP is absent. Here, we show that in Fmr1-deficient mice, RNA mis-splicing occurs in several brain regions and peripheral tissues. To assess molecular mechanisms of splicing mis-regulation, we employed N2A cells depleted of Fmr1. In the absence of FMRP, RNA-specific exon skipping events are linked to the splicing factors hnRNPF, PTBP1, and MBNL1. FMRP regulates the translation of Mbnl1 mRNA as well as Mbnl1 RNA auto-splicing. Elevated Mbnl1 auto-splicing in FMRP-deficient cells results in the loss of a nuclear localization signal (NLS)-containing exon. This in turn alters the nucleus-to-cytoplasm ratio of MBNL1. This redistribution of MBNL1 isoforms in Fmr1-deficient cells could result in downstream splicing changes in other RNAs. Indeed, further investigation revealed that splicing disruptions resulting from Fmr1 depletion could be rescued by overexpression of nuclear MBNL1. Altered Mbnl1 auto-splicing also occurs in human FXS postmortem brain. These data suggest that FMRP-controlled translation and RNA processing may cascade into a general dys-regulation of splicing in Fmr1-deficient cells.
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Affiliation(s)
- Suna Jung
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
| | - Sneha Shah
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
| | - Geongoo Han
- Molecular Microbiology and Immunology, Brown University, Providence, Rhode Island, United States of America
| | - Joel D. Richter
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
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3
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Verbeeren J, Teixeira J, Garcia SMDA. The Muscleblind-like protein MBL-1 regulates microRNA expression in Caenorhabditis elegans through an evolutionarily conserved autoregulatory mechanism. PLoS Genet 2023; 19:e1011109. [PMID: 38134228 PMCID: PMC10773944 DOI: 10.1371/journal.pgen.1011109] [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: 06/16/2023] [Revised: 01/08/2024] [Accepted: 12/12/2023] [Indexed: 12/24/2023] Open
Abstract
The Muscleblind-like (MBNL) family is a highly conserved set of RNA-binding proteins (RBPs) that regulate RNA metabolism during the differentiation of various animal tissues. Functional insufficiency of MBNL affects muscle and central nervous system development, and contributes to the myotonic dystrophies (DM), a set of incurable multisystemic disorders. Studies on the regulation of MBNL genes are essential to provide insight into the gene regulatory networks controlled by MBNL proteins and to understand how dysregulation within these networks causes disease. In this study, we demonstrate the evolutionary conservation of an autoregulatory mechanism that governs the function of MBNL proteins by generating two distinct protein isoform types through alternative splicing. Our aim was to further our understanding of the regulatory principles that underlie this conserved feedback loop in a whole-organismal context, and to address the biological significance of the respective isoforms. Using an alternative splicing reporter, our studies show that, during development of the Caenorhabditis elegans central nervous system, the orthologous mbl-1 gene shifts production from long protein isoforms that localize to the nucleus to short isoforms that also localize to the cytoplasm. Using isoform-specific CRISPR/Cas9-generated strains, we showed that expression of short MBL-1 protein isoforms is required for healthy neuromuscular function and neurodevelopment, while expression of long MBL-1 protein isoforms is dispensable, emphasizing a key role for cytoplasmic functionalities of the MBL-1 protein. Furthermore, RNA-seq and lifespan analyses indicated that short MBL-1 isoforms are crucial regulators of miRNA expression and, in consequence, required for normal lifespan. In conclusion, this study provides support for the disruption of cytoplasmic RNA metabolism as a contributor in myotonic dystrophy and paves the way for further exploration of miRNA regulation through MBNL proteins during development and in disease models.
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Affiliation(s)
- Jens Verbeeren
- Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki, Finland
| | - Joana Teixeira
- Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki, Finland
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4
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How does precursor RNA structure influence RNA processing and gene expression? Biosci Rep 2023; 43:232489. [PMID: 36689327 PMCID: PMC9977717 DOI: 10.1042/bsr20220149] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 01/17/2023] [Accepted: 01/23/2023] [Indexed: 01/24/2023] Open
Abstract
RNA is a fundamental biomolecule that has many purposes within cells. Due to its single-stranded and flexible nature, RNA naturally folds into complex and dynamic structures. Recent technological and computational advances have produced an explosion of RNA structural data. Many RNA structures have regulatory and functional properties. Studying the structure of nascent RNAs is particularly challenging due to their low abundance and long length, but their structures are important because they can influence RNA processing. Precursor RNA processing is a nexus of pathways that determines mature isoform composition and that controls gene expression. In this review, we examine what is known about human nascent RNA structure and the influence of RNA structure on processing of precursor RNAs. These known structures provide examples of how other nascent RNAs may be structured and show how novel RNA structures may influence RNA processing including splicing and polyadenylation. RNA structures can be targeted therapeutically to treat disease.
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5
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Alzheimer's Disease-Associated Alternative Splicing of CD33 Is Regulated by the HNRNPA Family Proteins. Cells 2023; 12:cells12040602. [PMID: 36831269 PMCID: PMC9954446 DOI: 10.3390/cells12040602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Revised: 02/07/2023] [Accepted: 02/09/2023] [Indexed: 02/16/2023] Open
Abstract
Genetic variations of CD33 have been implicated as a susceptibility factor of Alzheimer's disease (AD). A polymorphism on exon 2 of CD33, rs12459419, affects the alternative splicing of this exon. The minor allele is associated with a reduced risk of AD and promotes the skipping of exon 2 to produce a shorter CD33 isoform lacking the extracellular ligand-binding domain, leading to decreased suppressive signaling on microglial activity. Therefore, factors that regulate the splicing of exon 2 may alter the disease-associated properties of CD33. Herein, we sought to identify the regulatory proteins of CD33 splicing. Using a panel of RNA-binding proteins and a human CD33 minigene, we found that exon 2 skipping of CD33 was promoted by HNRNPA1. Although the knockdown of HNRNPA1 alone did not reduce exon 2 skipping, simultaneous knockdown of HNRNPA1 together with that of HNRNPA2B1 and HNRNPA3 promoted exon 2 inclusion, suggesting functional redundancy among HNRNPA proteins. Similar redundant regulation by HNRNPA proteins was observed in endogenous CD33 of THP-1 and human microglia-like cells. Although mouse Cd33 showed a unique splicing pattern of exon 2, we confirmed that HNRNPA1 promoted the skipping of this exon. Collectively, our results revealed novel regulatory relationships between CD33 and HNRNPA proteins.
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6
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Pamudurti NR, Patop IL, Krishnamoorthy A, Bartok O, Maya R, Lerner N, Ashwall-Fluss R, Konakondla JVV, Beatus T, Kadener S. circMbl functions in cis and in trans to regulate gene expression and physiology in a tissue-specific fashion. Cell Rep 2022; 39:110740. [PMID: 35476987 PMCID: PMC9352392 DOI: 10.1016/j.celrep.2022.110740] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 02/11/2022] [Accepted: 04/05/2022] [Indexed: 11/03/2022] Open
Abstract
Muscleblind (mbl) is an essential muscle and neuronal splicing regulator. Mbl hosts multiple circular RNAs (circRNAs), including circMbl, which is conserved from flies to humans. Here, we show that mbl-derived circRNAs are key regulators of MBL by cis- and trans-acting mechanisms. By generating fly lines to specifically modulate the levels of all mbl RNA isoforms, including circMbl, we demonstrate that the two major mbl protein isoforms, MBL-O/P and MBL-C, buffer their own levels by producing different types of circRNA isoforms in the eye and fly brain, respectively. Moreover, we show that circMbl has unique functions in trans, as knockdown of circMbl results in specific morphological and physiological phenotypes. In addition, depletion of MBL-C or circMbl results in opposite behavioral phenotypes, showing that they also regulate each other in trans. Together, our results illuminate key aspects of mbl regulation and uncover cis and trans functions of circMbl in vivo.
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Affiliation(s)
| | | | | | - Osnat Bartok
- Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Roni Maya
- The Rachel and Selim Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel; Department of Neurobiology, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Noam Lerner
- The Rachel and Selim Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel; Department of Neurobiology, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Reut Ashwall-Fluss
- Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | | | - Tsevi Beatus
- The Rachel and Selim Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel; Department of Neurobiology, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Sebastian Kadener
- Biology Department, Brandeis University, Waltham, MA 02454, USA; Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel.
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7
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Nikonova E, Mukherjee A, Kamble K, Barz C, Nongthomba U, Spletter ML. Rbfox1 is required for myofibril development and maintaining fiber type-specific isoform expression in Drosophila muscles. Life Sci Alliance 2022; 5:5/4/e202101342. [PMID: 34996845 PMCID: PMC8742874 DOI: 10.26508/lsa.202101342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 12/22/2021] [Accepted: 12/23/2021] [Indexed: 11/24/2022] Open
Abstract
Protein isoform transitions confer muscle fibers with distinct properties and are regulated by differential transcription and alternative splicing. RNA-binding Fox protein 1 (Rbfox1) can affect both transcript levels and splicing, and is known to contribute to normal muscle development and physiology in vertebrates, although the detailed mechanisms remain obscure. In this study, we report that Rbfox1 contributes to the generation of adult muscle diversity in Drosophila Rbfox1 is differentially expressed among muscle fiber types, and RNAi knockdown causes a hypercontraction phenotype that leads to behavioral and eclosion defects. Misregulation of fiber type-specific gene and splice isoform expression, notably loss of an indirect flight muscle-specific isoform of Troponin-I that is critical for regulating myosin activity, leads to structural defects. We further show that Rbfox1 directly binds the 3'-UTR of target transcripts, regulates the expression level of myogenic transcription factors myocyte enhancer factor 2 and Salm, and both modulates expression of and genetically interacts with the CELF family RNA-binding protein Bruno1 (Bru1). Rbfox1 and Bru1 co-regulate fiber type-specific alternative splicing of structural genes, indicating that regulatory interactions between FOX and CELF family RNA-binding proteins are conserved in fly muscle. Rbfox1 thus affects muscle development by regulating fiber type-specific splicing and expression dynamics of identity genes and structural proteins.
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Affiliation(s)
- Elena Nikonova
- Department of Physiological Chemistry, Biomedical Center, Ludwig-Maximilians-Universität München, Martinsried-Planegg, Germany
| | - Amartya Mukherjee
- Department of Molecular Reproduction, Development and Genetics (MRDG), Indian Institute of Science, Bangalore, India
| | - Ketaki Kamble
- Department of Molecular Reproduction, Development and Genetics (MRDG), Indian Institute of Science, Bangalore, India
| | - Christiane Barz
- Muscle Dynamics Group, Max Planck Institute of Biochemistry, Martinsried-Planegg, Germany
| | - Upendra Nongthomba
- Department of Molecular Reproduction, Development and Genetics (MRDG), Indian Institute of Science, Bangalore, India
| | - Maria L Spletter
- Department of Physiological Chemistry, Biomedical Center, Ludwig-Maximilians-Universität München, Martinsried-Planegg, Germany
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8
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Disrupting the Molecular Pathway in Myotonic Dystrophy. Int J Mol Sci 2021; 22:ijms222413225. [PMID: 34948025 PMCID: PMC8708683 DOI: 10.3390/ijms222413225] [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: 11/05/2021] [Revised: 12/03/2021] [Accepted: 12/06/2021] [Indexed: 01/26/2023] Open
Abstract
Myotonic dystrophy is the most common muscular dystrophy in adults. It consists of two forms: type 1 (DM1) and type 2 (DM2). DM1 is associated with a trinucleotide repeat expansion mutation, which is transcribed but not translated into protein. The mutant RNA remains in the nucleus, which leads to a series of downstream abnormalities. DM1 is widely considered to be an RNA-based disorder. Thus, we consider three areas of the RNA pathway that may offer targeting opportunities to disrupt the production, stability, and degradation of the mutant RNA.
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9
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Kao SY, Nikonova E, Chaabane S, Sabani A, Martitz A, Wittner A, Heemken J, Straub T, Spletter ML. A Candidate RNAi Screen Reveals Diverse RNA-Binding Protein Phenotypes in Drosophila Flight Muscle. Cells 2021; 10:2505. [PMID: 34685485 PMCID: PMC8534295 DOI: 10.3390/cells10102505] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 09/14/2021] [Accepted: 09/18/2021] [Indexed: 12/30/2022] Open
Abstract
The proper regulation of RNA processing is critical for muscle development and the fine-tuning of contractile ability among muscle fiber-types. RNA binding proteins (RBPs) regulate the diverse steps in RNA processing, including alternative splicing, which generates fiber-type specific isoforms of structural proteins that confer contractile sarcomeres with distinct biomechanical properties. Alternative splicing is disrupted in muscle diseases such as myotonic dystrophy and dilated cardiomyopathy and is altered after intense exercise as well as with aging. It is therefore important to understand splicing and RBP function, but currently, only a small fraction of the hundreds of annotated RBPs expressed in muscle have been characterized. Here, we demonstrate the utility of Drosophila as a genetic model system to investigate basic developmental mechanisms of RBP function in myogenesis. We find that RBPs exhibit dynamic temporal and fiber-type specific expression patterns in mRNA-Seq data and display muscle-specific phenotypes. We performed knockdown with 105 RNAi hairpins targeting 35 RBPs and report associated lethality, flight, myofiber and sarcomere defects, including flight muscle phenotypes for Doa, Rm62, mub, mbl, sbr, and clu. Knockdown phenotypes of spliceosome components, as highlighted by phenotypes for A-complex components SF1 and Hrb87F (hnRNPA1), revealed level- and temporal-dependent myofibril defects. We further show that splicing mediated by SF1 and Hrb87F is necessary for Z-disc stability and proper myofibril development, and strong knockdown of either gene results in impaired localization of kettin to the Z-disc. Our results expand the number of RBPs with a described phenotype in muscle and underscore the diversity in myofibril and transcriptomic phenotypes associated with splicing defects. Drosophila is thus a powerful model to gain disease-relevant insight into cellular and molecular phenotypes observed when expression levels of splicing factors, spliceosome components and splicing dynamics are altered.
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Affiliation(s)
- Shao-Yen Kao
- Biomedical Center, Department of Physiological Chemistry, Ludwig-Maximilians-Universität München, Großhaderner Str. 9, 82152 Martinsried-Planegg, Germany; (S.-Y.K.); (E.N.); (S.C.); (A.W.); (J.H.)
| | - Elena Nikonova
- Biomedical Center, Department of Physiological Chemistry, Ludwig-Maximilians-Universität München, Großhaderner Str. 9, 82152 Martinsried-Planegg, Germany; (S.-Y.K.); (E.N.); (S.C.); (A.W.); (J.H.)
| | - Sabrina Chaabane
- Biomedical Center, Department of Physiological Chemistry, Ludwig-Maximilians-Universität München, Großhaderner Str. 9, 82152 Martinsried-Planegg, Germany; (S.-Y.K.); (E.N.); (S.C.); (A.W.); (J.H.)
| | - Albiona Sabani
- Department of Biology, University of Wisconsin at Madison, 1117 W. Johnson St., Madison, WI 53706, USA;
| | - Alexandra Martitz
- Molecular Nutrition Medicine, Else Kröner-Fresenius Center, Technical University of Munich, 85354 Freising, Germany;
| | - Anja Wittner
- Biomedical Center, Department of Physiological Chemistry, Ludwig-Maximilians-Universität München, Großhaderner Str. 9, 82152 Martinsried-Planegg, Germany; (S.-Y.K.); (E.N.); (S.C.); (A.W.); (J.H.)
| | - Jakob Heemken
- Biomedical Center, Department of Physiological Chemistry, Ludwig-Maximilians-Universität München, Großhaderner Str. 9, 82152 Martinsried-Planegg, Germany; (S.-Y.K.); (E.N.); (S.C.); (A.W.); (J.H.)
| | - Tobias Straub
- Biomedical Center, Bioinformatics Core Facility, Ludwig-Maximilians-Universität München, Großhaderner Str. 9, 82152 Martinsried-Planegg, Germany;
| | - Maria L. Spletter
- Biomedical Center, Department of Physiological Chemistry, Ludwig-Maximilians-Universität München, Großhaderner Str. 9, 82152 Martinsried-Planegg, Germany; (S.-Y.K.); (E.N.); (S.C.); (A.W.); (J.H.)
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10
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Malik I, Kelley CP, Wang ET, Todd PK. Molecular mechanisms underlying nucleotide repeat expansion disorders. Nat Rev Mol Cell Biol 2021; 22:589-607. [PMID: 34140671 PMCID: PMC9612635 DOI: 10.1038/s41580-021-00382-6] [Citation(s) in RCA: 141] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/30/2021] [Indexed: 02/05/2023]
Abstract
The human genome contains over one million short tandem repeats. Expansion of a subset of these repeat tracts underlies over fifty human disorders, including common genetic causes of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (C9orf72), polyglutamine-associated ataxias and Huntington disease, myotonic dystrophy, and intellectual disability disorders such as Fragile X syndrome. In this Review, we discuss the four major mechanisms by which expansion of short tandem repeats causes disease: loss of function through transcription repression, RNA-mediated gain of function through gelation and sequestration of RNA-binding proteins, gain of function of canonically translated repeat-harbouring proteins, and repeat-associated non-AUG translation of toxic repeat peptides. Somatic repeat instability amplifies these mechanisms and influences both disease age of onset and tissue specificity of pathogenic features. We focus on the crosstalk between these disease mechanisms, and argue that they often synergize to drive pathogenesis. We also discuss the emerging native functions of repeat elements and how their dynamics might contribute to disease at a larger scale than currently appreciated. Lastly, we propose that lynchpins tying these disease mechanisms and native functions together offer promising therapeutic targets with potential shared applications across this class of human disorders.
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Affiliation(s)
- Indranil Malik
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Chase P Kelley
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics, Genetics Institute, University of Florida, Gainesville, FL, USA
- Genetics and Genomics Graduate Program, University of Florida, Gainesville, FL, USA
| | - Eric T Wang
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics, Genetics Institute, University of Florida, Gainesville, FL, USA.
| | - Peter K Todd
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA.
- VA Ann Arbor Healthcare System, Ann Arbor, MI, USA.
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11
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Ishiguro T, Nagai Y, Ishikawa K. Insight Into Spinocerebellar Ataxia Type 31 (SCA31) From Drosophila Model. Front Neurosci 2021; 15:648133. [PMID: 34113230 PMCID: PMC8185138 DOI: 10.3389/fnins.2021.648133] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 03/31/2021] [Indexed: 11/13/2022] Open
Abstract
Spinocerebellar ataxia type 31 (SCA31) is a progressive neurodegenerative disease characterized by degeneration of Purkinje cells in the cerebellum. Its genetic cause is a 2.5- to 3.8-kb-long complex pentanucleotide repeat insertion containing (TGGAA)n, (TAGAA)n, (TAAAA)n, and (TAAAATAGAA)n located in an intron shared by two different genes: brain expressed associated with NEDD4-1 (BEAN1) and thymidine kinase 2 (TK2). Among these repeat sequences, (TGGAA)n repeat was the only sequence segregating with SCA31, which strongly suggests its pathogenicity. In SCA31 patient brains, the mutant BEAN1 transcript containing expanded UGGAA repeats (UGGAAexp) was found to form abnormal RNA structures called RNA foci in cerebellar Purkinje cell nuclei. In addition, the deposition of pentapeptide repeat (PPR) proteins, poly(Trp-Asn-Gly-Met-Glu), translated from UGGAAexp RNA, was detected in the cytoplasm of Purkinje cells. To uncover the pathogenesis of UGGAAexp in SCA31, we generated Drosophila models of SCA31 expressing UGGAAexp RNA. The toxicity of UGGAAexp depended on its length and expression level, which was accompanied by the accumulation of RNA foci and translation of repeat-associated PPR proteins in Drosophila, consistent with the observation in SCA31 patient brains. We also revealed that TDP-43, FUS, and hnRNPA2B1, motor neuron disease–linked RNA-binding proteins bound to UGGAAexp RNA, act as RNA chaperones to regulate the formation of RNA foci and repeat-associated translation. Further research on the role of RNA-binding proteins as RNA chaperones may also provide a novel therapeutic strategy for other microsatellite repeat expansion diseases besides SCA31.
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Affiliation(s)
- Taro Ishiguro
- Department of Neurology and Neurological Science, Tokyo Medical and Dental University, Bunkyo City, Japan
| | - Yoshitaka Nagai
- Department of Neurotherapeutics, Osaka University Graduate School of Medicine, Suita, Japan
| | - Kinya Ishikawa
- Department of Neurology and Neurological Science, Tokyo Medical and Dental University, Bunkyo City, Japan.,Department of Personalized Genomic Medicine for Health, Graduate School, Tokyo Medical and Dental University, Bunkyo City, Japan
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12
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Malnar M, Rogelj B. SFPQ regulates the accumulation of RNA foci and dipeptide repeat proteins from the expanded repeat mutation in C9orf72. J Cell Sci 2021; 134:jcs.256602. [PMID: 33495278 PMCID: PMC7904093 DOI: 10.1242/jcs.256602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 01/08/2021] [Indexed: 12/12/2022] Open
Abstract
The expanded GGGGCC repeat mutation in the C9orf72 gene is the most common genetic cause of the neurodegenerative diseases amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The expansion is transcribed to sense and antisense RNA, which form RNA foci and bind cellular proteins. This mechanism of action is considered cytotoxic. Translation of the expanded RNA transcripts also leads to the accumulation of toxic dipeptide repeat proteins (DPRs). The RNA-binding protein splicing factor proline and glutamine rich (SFPQ), which is being increasingly associated with ALS and FTD pathology, binds to sense RNA foci. Here, we show that SFPQ plays an important role in the C9orf72 mutation. Overexpression of SFPQ resulted in higher numbers of both sense and antisense RNA foci and DPRs in transfected human embryonic kidney (HEK) cells. Conversely, reduced SPFQ levels resulted in lower numbers of RNA foci and DPRs in both transfected HEK cells and C9orf72 mutation-positive patient-derived fibroblasts and lymphoblasts. Therefore, we have revealed a role of SFPQ in regulating the C9orf72 mutation that has implications for understanding and developing novel therapeutic targets for ALS and FTD. This article has an associated First Person interview with the first author of the paper. Summary: Expression level modulation of the core paraspeckle protein SFPQ regulates sense and antisense RNA foci and dipeptide repeat protein accumulation in the C9orf72 mutation; SFPQ could be a therapeutic target in C9orf72 ALS and FTD.
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Affiliation(s)
- Mirjana Malnar
- Department of Biotechnology, Jožef Stefan Institute, 1000 Ljubljana, Slovenia.,Graduate School of Biomedicine, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Boris Rogelj
- Department of Biotechnology, Jožef Stefan Institute, 1000 Ljubljana, Slovenia .,Biomedical Research Institute, 1000 Ljubljana, Slovenia.,Faculty of Chemistry and Chemical Engineering, University of Ljubljana, 1000 Ljubljana, Slovenia
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13
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Ozimski LL, Sabater-Arcis M, Bargiela A, Artero R. The hallmarks of myotonic dystrophy type 1 muscle dysfunction. Biol Rev Camb Philos Soc 2020; 96:716-730. [PMID: 33269537 DOI: 10.1111/brv.12674] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 11/18/2020] [Accepted: 11/20/2020] [Indexed: 12/20/2022]
Abstract
Myotonic dystrophy type 1 (DM1) is the most prevalent form of muscular dystrophy in adults and yet there are currently no treatment options. Although this disease causes multisystemic symptoms, it is mainly characterised by myopathy or diseased muscles, which includes muscle weakness, atrophy, and myotonia, severely affecting the lives of patients worldwide. On a molecular level, DM1 is caused by an expansion of CTG repeats in the 3' untranslated region (3'UTR) of the DM1 Protein Kinase (DMPK) gene which become pathogenic when transcribed into RNA forming ribonuclear foci comprised of auto complementary CUG hairpin structures that can bind proteins. This leads to the sequestration of the muscleblind-like (MBNL) family of proteins, depleting them, and the abnormal stabilisation of CUGBP Elav-like family member 1 (CELF1), enhancing it. Traditionally, DM1 research has focused on this RNA toxicity and how it alters MBNL and CELF1 functions as key splicing regulators. However, other proteins are affected by the toxic DMPK RNA and there is strong evidence that supports various signalling cascades playing an important role in DM1 pathogenesis. Specifically, the impairment of protein kinase B (AKT) signalling in DM1 increases autophagy, apoptosis, and ubiquitin-proteasome activity, which may also be affected in DM1 by AMP-activated protein kinase (AMPK) downregulation. AKT also regulates CELF1 directly, by affecting its subcellular localisation, and indirectly as it inhibits glycogen synthase kinase 3 beta (GSK3β), which stabilises the repressive form of CELF1 in DM1. Another kinase that contributes to CELF1 mis-regulation, in this case by hyperphosphorylation, is protein kinase C (PKC). Additionally, it has been demonstrated that fibroblast growth factor-inducible 14 (Fn14) is induced in DM1 and is associated with downstream signalling through the nuclear factor κB (NFκB) pathways, associating inflammation with this disease. Furthermore, MBNL1 and CELF1 play a role in cytoplasmic processes involved in DM1 myopathy, altering proteostasis and sarcomere structure. Finally, there are many other elements that could contribute to the muscular phenotype in DM1 such as alterations to satellite cells, non-coding RNA metabolism, calcium dysregulation, and repeat-associated non-ATG (RAN) translation. This review aims to organise the currently dispersed knowledge on the different pathways affected in DM1 and discusses the unexplored connections that could potentially help in providing new therapeutic targets in DM1 research.
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Affiliation(s)
- Lauren L Ozimski
- Translational Genomics Group, Incliva Health Research Institute, Avda. Menéndez Pelayo 4 acc., Valencia, 46010, Spain.,University Institute for Biotechnology and Biomedicine, Dr. Moliner 50, Burjasot, Valencia, 46100, Spain.,CIPF-INCLIVA Joint Unit, Valencia, 46012, Spain.,Arthex Biotech, Catedrático Escardino, 9, Paterna, Valencia, 46980, Spain
| | - Maria Sabater-Arcis
- Translational Genomics Group, Incliva Health Research Institute, Avda. Menéndez Pelayo 4 acc., Valencia, 46010, Spain.,University Institute for Biotechnology and Biomedicine, Dr. Moliner 50, Burjasot, Valencia, 46100, Spain.,CIPF-INCLIVA Joint Unit, Valencia, 46012, Spain
| | - Ariadna Bargiela
- Translational Genomics Group, Incliva Health Research Institute, Avda. Menéndez Pelayo 4 acc., Valencia, 46010, Spain.,University Institute for Biotechnology and Biomedicine, Dr. Moliner 50, Burjasot, Valencia, 46100, Spain.,CIPF-INCLIVA Joint Unit, Valencia, 46012, Spain
| | - Ruben Artero
- Translational Genomics Group, Incliva Health Research Institute, Avda. Menéndez Pelayo 4 acc., Valencia, 46010, Spain.,University Institute for Biotechnology and Biomedicine, Dr. Moliner 50, Burjasot, Valencia, 46100, Spain.,CIPF-INCLIVA Joint Unit, Valencia, 46012, Spain
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14
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CELF2 regulates the species-specific alternative splicing of TREM2. Sci Rep 2020; 10:17995. [PMID: 33093587 PMCID: PMC7582162 DOI: 10.1038/s41598-020-75057-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Accepted: 10/12/2020] [Indexed: 11/08/2022] Open
Abstract
Genetic variations of TREM2 have been implicated as a risk factor of Alzheimer’s disease (AD). Recent studies suggest that the loss of TREM2 function compromises microglial responses to the accumulation of amyloid beta. Previously, we found that exon 3 of TREM2 is an alternative exon whose skipping leads to a reduction in full-length TREM2 protein by inducing nonsense-mediated mRNA decay. Here, we aimed to identify factors regulating TREM2 splicing. Using a panel of RNA-binding proteins, we found that exon 3 skipping of TREM2 was promoted by two paralogous proteins, CELF1 and CELF2, which were both linked previously with risk loci of AD. Although the overexpression of both CELF1 and CELF2 enhanced exon 3 skipping, only CELF2 reduced the expression of full-length TREM2 protein. Notably, the TREM2 ortholog in the green monkey, but not in the mouse, showed alternative splicing of exon 3 like human TREM2. Similarly, splicing regulation of exon 3 by CELF1/2 was found to be common to humans and monkeys. Using chimeric minigenes of human and mouse TREM2, we mapped a CELF-responsive sequence within intron 3 of human TREM2. Collectively, our results revealed a novel regulatory factor of TREM2 expression and highlighted a species-dependent difference of its regulation.
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15
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Chen YS, Liu CW, Lin YC, Tsai CY, Yang CH, Lin JC. The SRSF3-MBNL1-Acin1 circuit constitutes an emerging axis to lessen DNA fragmentation in colorectal cancer via an alternative splicing mechanism. Neoplasia 2020; 22:702-713. [PMID: 33142236 PMCID: PMC7586066 DOI: 10.1016/j.neo.2020.10.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 09/30/2020] [Accepted: 10/04/2020] [Indexed: 02/07/2023] Open
Abstract
Altered alternative splicing (AS) events are considered pervasive causes that result in the development of carcinogenesis. Herein, we identified reprogrammed expression and splicing profiles of Muscle blind-like protein 1 (MBNL1) transcripts in tumorous tissues compared to those of adjacent normal tissues dissected from individual colorectal cancer (CRC) patients using whole-transcriptome analyses. MBNL1 transcript 8 (MBNL18) containing exons 5 and 7 was majorly generated by cancerous tissues and CRC-derived cell lines compared with those of the normal counterparts. Interplay between the exonic CA-rich element and upregulated SRSF3 facilitated the inclusion of MBNL1 exons 5 and 7, which encode a bipartite nuclear localization signal (NLS) and conformational NLS. Moreover, abundant SRSF3 interfered with the autoregulatory mechanism involved in utilization of MBNL1 exons 5 and 7, resulting in enrichment of the MBNL18 isoform in cultured CRC cell lines. Subsequently, an increase in the MBNL18 isoform drove a shift in the apoptotic chromatin condensation inducer in nucleus 1-S (Acin1-S) isoform to the Acin1-L isoform, leading to diminished DNA fragmentation in cultured CRC cells under oxidative stress. Taken together, SRSF3-MBNL1-Acin1 was demonstrated to constitute an emerging axis which is relevant to proapoptotic signatures and post-transcriptional events of CRC cells.
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Affiliation(s)
- Yi-Su Chen
- Department of Family Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
| | - Chao-Wei Liu
- Ph.D. Program in Medical Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan; Department of Laboratory Science, National Taiwan University Hospital, Taipei, Taiwan
| | - Ying-Chin Lin
- Department of Family Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan; Department of Family Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Chia-Ying Tsai
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
| | - Ching-Hui Yang
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
| | - Jung-Chun Lin
- Ph.D. Program in Medical Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan; School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan; Pulmonary Research Center, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan.
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16
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de la Fuente L, Arzalluz-Luque Á, Tardáguila M, Del Risco H, Martí C, Tarazona S, Salguero P, Scott R, Lerma A, Alastrue-Agudo A, Bonilla P, Newman JRB, Kosugi S, McIntyre LM, Moreno-Manzano V, Conesa A. tappAS: a comprehensive computational framework for the analysis of the functional impact of differential splicing. Genome Biol 2020; 21:119. [PMID: 32423416 PMCID: PMC7236505 DOI: 10.1186/s13059-020-02028-w] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 04/23/2020] [Indexed: 12/26/2022] Open
Abstract
Recent advances in long-read sequencing solve inaccuracies in alternative transcript identification of full-length transcripts in short-read RNA-Seq data, which encourages the development of methods for isoform-centered functional analysis. Here, we present tappAS, the first framework to enable a comprehensive Functional Iso-Transcriptomics (FIT) analysis, which is effective at revealing the functional impact of context-specific post-transcriptional regulation. tappAS uses isoform-resolved annotation of coding and non-coding functional domains, motifs, and sites, in combination with novel analysis methods to interrogate different aspects of the functional readout of transcript variants and isoform regulation. tappAS software and documentation are available at https://app.tappas.org.
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Affiliation(s)
- Lorena de la Fuente
- Genomics of Gene Expression Laboratory, Prince Felipe Research Center, Valencia, Spain
- Present Address: Bioinformatics Unit, IIS Fundación Jiménez Díaz, Madrid, Spain
| | - Ángeles Arzalluz-Luque
- Department of Statistics and Operational Research, Polytechnical University of Valencia, Valencia, Spain
| | - Manuel Tardáguila
- Department of Microbiology and Cell Science, Institute for Food and Agricultural Sciences, University of Florida, Gainesville, FL, USA
- Present Address: Human Genetics Department, Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK
| | - Héctor Del Risco
- Department of Microbiology and Cell Science, Institute for Food and Agricultural Sciences, University of Florida, Gainesville, FL, USA
| | - Cristina Martí
- Genomics of Gene Expression Laboratory, Prince Felipe Research Center, Valencia, Spain
| | - Sonia Tarazona
- Department of Statistics and Operational Research, Polytechnical University of Valencia, Valencia, Spain
| | - Pedro Salguero
- Genomics of Gene Expression Laboratory, Prince Felipe Research Center, Valencia, Spain
| | - Raymond Scott
- Department of Microbiology and Cell Science, Institute for Food and Agricultural Sciences, University of Florida, Gainesville, FL, USA
| | - Alberto Lerma
- Genomics of Gene Expression Laboratory, Prince Felipe Research Center, Valencia, Spain
| | - Ana Alastrue-Agudo
- Present Address: Human Genetics Department, Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK
| | - Pablo Bonilla
- Present Address: Human Genetics Department, Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK
| | - Jeremy R B Newman
- Genetics Institute, University of Florida, Gainesville, FL, USA
- Department of Pathology, University of Florida, Gainesville, FL, USA
| | - Shunichi Kosugi
- Genetics Institute, University of Florida, Gainesville, FL, USA
- Laboratory for Statistical and Translational Genetics, Center for Integrative Medical Sciences, RIKEN, Wako, Japan
| | - Lauren M McIntyre
- Genetics Institute, University of Florida, Gainesville, FL, USA
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL, USA
| | | | - Ana Conesa
- Department of Microbiology and Cell Science, Institute for Food and Agricultural Sciences, University of Florida, Gainesville, FL, USA.
- Genetics Institute, University of Florida, Gainesville, FL, USA.
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17
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Stepniak-Konieczna E, Konieczny P, Cywoniuk P, Dluzewska J, Sobczak K. AON-induced splice-switching and DMPK pre-mRNA degradation as potential therapeutic approaches for Myotonic Dystrophy type 1. Nucleic Acids Res 2020; 48:2531-2543. [PMID: 31965181 PMCID: PMC7049696 DOI: 10.1093/nar/gkaa007] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 12/28/2019] [Accepted: 01/03/2020] [Indexed: 01/04/2023] Open
Abstract
Expansion of an unstable CTG repeat in the 3′UTR of the DMPK gene causes Myotonic Dystrophy type 1 (DM1). CUG-expanded DMPK transcripts (CUGexp) sequester Muscleblind-like (MBNL) alternative splicing regulators in ribonuclear inclusions (foci), leading to abnormalities in RNA processing and splicing. To alleviate the burden of CUGexp, we tested therapeutic approach utilizing antisense oligonucleotides (AONs)-mediated DMPK splice-switching and degradation of mutated pre-mRNA. Experimental design involved: (i) skipping of selected constitutive exons to induce frameshifting and decay of toxic mRNAs by an RNA surveillance mechanism, and (ii) exclusion of the alternative exon 15 (e15) carrying CUGexp from DMPK mRNA. While first strategy failed to stimulate DMPK mRNA decay, exclusion of e15 enhanced DMPK nuclear export but triggered accumulation of potentially harmful spliced out pre-mRNA fragment containing CUGexp. Neutralization of this fragment with antisense gapmers complementary to intronic sequences preceding e15 failed to diminish DM1-specific spliceopathy due to AONs’ chemistry-related toxicity. However, intronic gapmers alone reduced the level of DMPK mRNA and mitigated DM1-related cellular phenotypes including spliceopathy and nuclear foci. Thus, a combination of the correct chemistry and experimental approach should be carefully considered to design a safe AON-based therapeutic strategy for DM1.
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Affiliation(s)
- Ewa Stepniak-Konieczna
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University in Poznan, Uniwersytetu Poznanskiego 6, 61-614 Poznan, Poland
| | - Patryk Konieczny
- Institute of Human Biology and Evolution, Faculty of Biology, Adam Mickiewicz University in Poznan, Uniwersytetu Poznanskiego 6, 61-614 Poznan, Poland
| | - Piotr Cywoniuk
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University in Poznan, Uniwersytetu Poznanskiego 6, 61-614 Poznan, Poland
| | - Julia Dluzewska
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University in Poznan, Uniwersytetu Poznanskiego 6, 61-614 Poznan, Poland
| | - Krzysztof Sobczak
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University in Poznan, Uniwersytetu Poznanskiego 6, 61-614 Poznan, Poland
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18
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Thomas JD, Polaski JT, Feng Q, De Neef EJ, Hoppe ER, McSharry MV, Pangallo J, Gabel AM, Belleville AE, Watson J, Nkinsi NT, Berger AH, Bradley RK. RNA isoform screens uncover the essentiality and tumor-suppressor activity of ultraconserved poison exons. Nat Genet 2020; 52:84-94. [PMID: 31911676 PMCID: PMC6962552 DOI: 10.1038/s41588-019-0555-z] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 11/21/2019] [Indexed: 12/30/2022]
Abstract
While RNA-seq has enabled comprehensive quantification of alternative splicing, no correspondingly high-throughput assay exists for functionally interrogating individual isoforms. We describe pgFARM (paired guide RNAs for alternative exon removal), a CRISPR-Cas9-based method to manipulate isoforms independent of gene inactivation. This approach enabled rapid suppression of exon recognition in polyclonal settings to identify functional roles for individual exons, such as an SMNDC1 cassette exon that regulates pan-cancer intron retention. We generalized this method to a pooled screen to measure the functional relevance of 'poison' cassette exons, which disrupt their host genes' reading frames yet are frequently ultraconserved. Many poison exons were essential for the growth of both cultured cells and lung adenocarcinoma xenografts, while a subset had clinically relevant tumor-suppressor activity. The essentiality and cancer relevance of poison exons are likely to contribute to their unusually high conservation and contrast with the dispensability of other ultraconserved elements for viability.
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Affiliation(s)
- James D Thomas
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Jacob T Polaski
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Qing Feng
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Emma J De Neef
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Emma R Hoppe
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Maria V McSharry
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Joseph Pangallo
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Austin M Gabel
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
- Medical Scientist Training Program, University of Washington, Seattle, WA, USA
| | - Andrea E Belleville
- Medical Scientist Training Program, University of Washington, Seattle, WA, USA
| | - Jacqueline Watson
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Naomi T Nkinsi
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Alice H Berger
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
- Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Robert K Bradley
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA.
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA.
- Department of Genome Sciences, University of Washington, Seattle, WA, USA.
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19
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Christou M, Wengel J, Sokratous K, Kyriacou K, Nikolaou G, Phylactou LA, Mastroyiannopoulos NP. Systemic Evaluation of Chimeric LNA/2'-O-Methyl Steric Blockers for Myotonic Dystrophy Type 1 Therapy. Nucleic Acid Ther 2019; 30:80-93. [PMID: 31873063 PMCID: PMC7133450 DOI: 10.1089/nat.2019.0811] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a dominantly inherited, multisystemic disorder characterized clinically by delayed muscle relaxation and weakness. The disease is caused by a CTG repeat expansion in the 3′ untranslated region (3′ UTR) of the DMPK gene, which leads to the expression of a toxic gain-of-function mRNA. The expanded CUG repeat mRNA sequesters the MBNL1 splicing regulator in nuclear-retained foci structures, resulting in loss of protein function and disruption of alternative splicing homeostasis. In this study, we used CAG repeat antisense oligonucleotides (ASOs), composed of locked nucleic acid (LNA)- and 2′-O-methyl (2′OMe)-modified bases in a chimeric design, to alleviate CUGexpanded-mediated toxicity. Chimeric 14–18mer LNA/2′OMe oligonucleotides, exhibiting an LNA incorporation of ∼33%, significantly ameliorated the misregulated alternative splicing of Mbnl1-dependent exons in primary DM1 mouse myoblasts and tibialis anterior muscles of DM1 mice. Subcutaneous delivery of 14mer and 18mer LNA/2′OMe chimeras in DM1 mice resulted in high levels of accumulation in all tested skeletal muscles, as well as in the diaphragm and heart tissue. Despite the efficient delivery, chimeric LNA/2′OMe oligonucleotides were not able, even at a high-dosage regimen (400 mg/kg/week), to correct the misregulated splicing of Serca1 exon 22 in skeletal muscles. Nevertheless, oligonucleotide doses were well-tolerated as determined by histological and plasma biochemistry analyses. Our results provide proof of concept that inhibition of MBNL1 sequestration by systemic delivery of a steric-blocking ASO is extremely challenging, considering the large number of target sites that need to be occupied per RNA molecule. Although not suitable for DM1 therapy, chimeric LNA/2′OMe oligonucleotides could prove to be highly beneficial for other diseases, such as Duchenne muscular dystrophy, that require inhibition of a single target site per RNA molecule.
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Affiliation(s)
- Melina Christou
- Department of Molecular Genetics, Function & Therapy, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus.,The Cyprus School of Molecular Medicine, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Jesper Wengel
- Department of Physics, Chemistry and Pharmacy, Biomolecular Nanoscale Engineering Center, University of Southern Denmark, Odense M, Denmark
| | - Kleitos Sokratous
- Department of Electron Microscopy and Molecular Pathology, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus.,Bioinformatics Group, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Kyriacos Kyriacou
- The Cyprus School of Molecular Medicine, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus.,Department of Electron Microscopy and Molecular Pathology, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Georgios Nikolaou
- Veterinary Diagnostic Laboratory, Vet Ex Machina Ltd, Nicosia, Cyprus
| | - Leonidas A Phylactou
- Department of Molecular Genetics, Function & Therapy, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus.,The Cyprus School of Molecular Medicine, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Nikolaos P Mastroyiannopoulos
- Department of Molecular Genetics, Function & Therapy, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus.,The Cyprus School of Molecular Medicine, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
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20
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Hung CS, Lin JC. Alternatively spliced MBNL1 isoforms exhibit differential influence on enhancing brown adipogenesis. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2019; 1863:194437. [PMID: 31730826 DOI: 10.1016/j.bbagrm.2019.194437] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 09/23/2019] [Accepted: 09/25/2019] [Indexed: 01/15/2023]
Abstract
Browning of white adipocytes (WAs) (also referred as beige cells) was demonstrated to execute thermogenesis by consuming stored lipids as do brown adipocytes (BAs), and this is highly related to metabolic homeostasis. Alternative splicing (AS) constitutes a pivotal mechanism for defining cellular fates and functional specifications. Nevertheless, the impacts of AS regulation on the browning of WAs have not been comprehensively investigated. In this study, we first identified the discriminative expression and splicing profiles of the muscleblind-like 1 (MBNL1) gene in postnatal brown adipose tissues (BATs) compared to those of embryonic BATs. A shift in the MBNL1+ex 5 isoform 7 (MBNL17) to MBNL1-ex 5 isoform 1 (MBNL11) was characterized throughout BAT development or during the in vitro browning of pre-WAs, 3T3-L1 cells. The interplay between MBNL1 and the exonic CCUG motif constitutes an autoregulatory mechanism for excluding MBNL1 exon 5. The simultaneous association of RNA-binding motif protein 4a (RBM4a) with exonic and intronic CU elements collaboratively mediates the skipping of MBNL1 exon 5. Overexpressing the MBNL11 isoform exhibited a more-prominent effect than that of the MBNL17 isoform on programming its own transcripts and beige cell-related splicing events in a CCUG motif-mediated manner. In addition to splicing regulation, overexpression of the MBNL11 and MBNL17 isoforms differentially enhanced beige adipogenic signatures of 3T3-L1 cells. Our findings demonstrated that MBNL1 constitutes an emerging and autoregulatory mechanism involved in development of beige cells.
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Affiliation(s)
- Ching-Sheng Hung
- PhD Program in Medicine Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan; Department of Laboratory Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
| | - Jung-Chun Lin
- PhD Program in Medicine Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan; School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan.
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21
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Mori S, Honda H, Ishii T, Yoshimura M, Sasagasako N, Suzuki SO, Taniwaki T, Iwaki T. Expanded polyglutamine impairs normal nuclear distribution of fused in sarcoma and poly (rC)‐binding protein 1 in Huntington's disease. Neuropathology 2019; 39:358-367. [DOI: 10.1111/neup.12600] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 07/25/2019] [Accepted: 08/08/2019] [Indexed: 12/14/2022]
Affiliation(s)
- Shinichiro Mori
- Department of NeuropathologyGraduate School of Medical Sciences, Kyushu University Fukuoka Japan
- Department of Neurology, Division of Respirology, Neurology and Rheumatology, Department of MedicineKurume University School of Medicine Kurume Japan
| | - Hiroyuki Honda
- Department of NeuropathologyGraduate School of Medical Sciences, Kyushu University Fukuoka Japan
| | - Takashi Ishii
- Department of BiochemistryFukuoka Dental College Fukuoka Japan
| | - Motoi Yoshimura
- Department of NeuropathologyGraduate School of Medical Sciences, Kyushu University Fukuoka Japan
| | - Naokazu Sasagasako
- Department of NeurologyNeuro‐Muscular Center, National Omuta Hospital Omuta Japan
| | - Satoshi O. Suzuki
- Department of NeuropathologyGraduate School of Medical Sciences, Kyushu University Fukuoka Japan
| | - Takayuki Taniwaki
- Department of Neurology, Division of Respirology, Neurology and Rheumatology, Department of MedicineKurume University School of Medicine Kurume Japan
| | - Toru Iwaki
- Department of NeuropathologyGraduate School of Medical Sciences, Kyushu University Fukuoka Japan
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22
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Sznajder ŁJ, Swanson MS. Short Tandem Repeat Expansions and RNA-Mediated Pathogenesis in Myotonic Dystrophy. Int J Mol Sci 2019; 20:ijms20133365. [PMID: 31323950 PMCID: PMC6651174 DOI: 10.3390/ijms20133365] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 06/27/2019] [Accepted: 07/08/2019] [Indexed: 12/23/2022] Open
Abstract
Short tandem repeat (STR) or microsatellite, expansions underlie more than 50 hereditary neurological, neuromuscular and other diseases, including myotonic dystrophy types 1 (DM1) and 2 (DM2). Current disease models for DM1 and DM2 propose a common pathomechanism, whereby the transcription of mutant DMPK (DM1) and CNBP (DM2) genes results in the synthesis of CUG and CCUG repeat expansion (CUGexp, CCUGexp) RNAs, respectively. These CUGexp and CCUGexp RNAs are toxic since they promote the assembly of ribonucleoprotein (RNP) complexes or RNA foci, leading to sequestration of Muscleblind-like (MBNL) proteins in the nucleus and global dysregulation of the processing, localization and stability of MBNL target RNAs. STR expansion RNAs also form phase-separated gel-like droplets both in vitro and in transiently transfected cells, implicating RNA-RNA multivalent interactions as drivers of RNA foci formation. Importantly, the nucleation and growth of these nuclear foci and transcript misprocessing are reversible processes and thus amenable to therapeutic intervention. In this review, we provide an overview of potential DM1 and DM2 pathomechanisms, followed by a discussion of MBNL functions in RNA processing and how multivalent interactions between expanded STR RNAs and RNA-binding proteins (RBPs) promote RNA foci assembly.
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Affiliation(s)
- Łukasz J Sznajder
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA.
| | - Maurice S Swanson
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
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23
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Pervouchine D, Popov Y, Berry A, Borsari B, Frankish A, Guigó R. Integrative transcriptomic analysis suggests new autoregulatory splicing events coupled with nonsense-mediated mRNA decay. Nucleic Acids Res 2019; 47:5293-5306. [PMID: 30916337 PMCID: PMC6547761 DOI: 10.1093/nar/gkz193] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 03/12/2019] [Indexed: 11/12/2022] Open
Abstract
Nonsense-mediated decay (NMD) is a eukaryotic mRNA surveillance system that selectively degrades transcripts with premature termination codons (PTC). Many RNA-binding proteins (RBP) regulate their expression levels by a negative feedback loop, in which RBP binds its own pre-mRNA and causes alternative splicing to introduce a PTC. We present a bioinformatic analysis integrating three data sources, eCLIP assays for a large RBP panel, shRNA inactivation of NMD pathway, and shRNA-depletion of RBPs followed by RNA-seq, to identify novel such autoregulatory feedback loops. We show that RBPs frequently bind their own pre-mRNAs, their exons respond prominently to NMD pathway disruption, and that the responding exons are enriched with nearby eCLIP peaks. We confirm previously proposed models of autoregulation in SRSF7 and U2AF1 genes and present two novel models, in which (i) SFPQ binds its mRNA and promotes switching to an alternative distal 3'-UTR that is targeted by NMD, and (ii) RPS3 binding activates a poison 5'-splice site in its pre-mRNA that leads to a frame shift and degradation by NMD. We also suggest specific splicing events that could be implicated in autoregulatory feedback loops in RBM39, HNRNPM, and U2AF2 genes. The results are available through a UCSC Genome Browser track hub.
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Affiliation(s)
- Dmitri Pervouchine
- Skolkovo Institute of Science and Technology, Ulitsa Nobelya 3, Moscow 121205, Russia
- Faculty of Bioengineering and Bioinformatics, Moscow State University, Leninskiye Gory 1-73, 119234 Moscow, Russia
| | - Yaroslav Popov
- Faculty of Bioengineering and Bioinformatics, Moscow State University, Leninskiye Gory 1-73, 119234 Moscow, Russia
| | - Andy Berry
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, CB10 1SA Hinxton, Cambridge, UK
| | - Beatrice Borsari
- Center for Genomic Regulation, The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain
| | - Adam Frankish
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, CB10 1SA Hinxton, Cambridge, UK
| | - Roderic Guigó
- Center for Genomic Regulation, The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain
- Universitat Pompeu Fabra (UPF), Barcelona 08003, Spain
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24
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André LM, van Cruchten RTP, Willemse M, Wansink DG. (CTG)n repeat-mediated dysregulation of MBNL1 and MBNL2 expression during myogenesis in DM1 occurs already at the myoblast stage. PLoS One 2019; 14:e0217317. [PMID: 31116797 PMCID: PMC6530876 DOI: 10.1371/journal.pone.0217317] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 05/08/2019] [Indexed: 11/18/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a severe neuromuscular disorder caused by the expression of trinucleotide repeat-containing DMPK transcripts. Abnormally expanded (CUG)n repeats in these transcripts form hairpin-like structures that cause the RNA to accumulate in the cell nucleus by sequestering isoforms of the Muscleblind (MBNL) family, tissue-specific regulators of developmentally programmed, post-transcriptional processes in RNA metabolism. Through this mechanism, the function of MBNL in RNA processing becomes dominantly perturbed, which eventually leads to aberrant alternative splicing and the expression of foetal splice variants of a wide variety of proteins, including the MBNL isoforms themselves. Here, we employ a patient-derived muscle cell model for DM1 to examine in detail the expression of MBNL RNA and protein variants during myogenic differentiation. This DM1 model consists of a panel of isogenic myoblast cell lines that either contain a pathogenic DMPK allele with a congenital mutation of 2600 triplets, or lack this expanded repeat through CRISPR/Cas9-mediated gene editing. We found that the temporal expression levels of MBNL1, MBNL2 and MBNL3 RNAs are not influenced by presence of the (CTG)2600 repeat during myogenesis in vitro. However, throughout myoblast proliferation and differentiation to myotubes a disproportionate inclusion of MBNL1 exon 5 and MBNL2 exons 5 and 8 occurs in cells with the (CTG)2600 repeat. As a consequence, a reduced quantity and imbalanced collection of splice variants of MBNL1 and MBNL2 accumulates in both the cytoplasm and the nucleus of DM1 myoblasts and myotubes. We thus propose that both the quantitative and qualitative changes in the intracellular partitioning of MBNL proteins are a pivotal cause of skeletal muscle problems in DM1, starting already in muscle progenitor cells.
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Affiliation(s)
- Laurène M. André
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Department of Cell Biology, Nijmegen, The Netherlands
| | - Remco T. P. van Cruchten
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Department of Cell Biology, Nijmegen, The Netherlands
| | - Marieke Willemse
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Department of Cell Biology, Nijmegen, The Netherlands
| | - Derick G. Wansink
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Department of Cell Biology, Nijmegen, The Netherlands
- * E-mail:
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25
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Mitsuhashi S, Frith MC, Mizuguchi T, Miyatake S, Toyota T, Adachi H, Oma Y, Kino Y, Mitsuhashi H, Matsumoto N. Tandem-genotypes: robust detection of tandem repeat expansions from long DNA reads. Genome Biol 2019; 20:58. [PMID: 30890163 PMCID: PMC6425644 DOI: 10.1186/s13059-019-1667-6] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 03/01/2019] [Indexed: 01/03/2023] Open
Abstract
Tandemly repeated DNA is highly mutable and causes at least 31 diseases, but it is hard to detect pathogenic repeat expansions genome-wide. Here, we report robust detection of human repeat expansions from careful alignments of long but error-prone (PacBio and nanopore) reads to a reference genome. Our method is robust to systematic sequencing errors, inexact repeats with fuzzy boundaries, and low sequencing coverage. By comparing to healthy controls, we prioritize pathogenic expansions within the top 10 out of 700,000 tandem repeats in whole genome sequencing data. This may help to elucidate the many genetic diseases whose causes remain unknown.
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Affiliation(s)
- Satomi Mitsuhashi
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Fukuura 3-9, Kanazawa-ku, Yokohama, 236-0004, Japan.
| | - Martin C Frith
- Artificial Intelligence Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 2-3-26 Aomi, Koto-ku, Tokyo, 135-0064, Japan.
- Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba, Japan.
- Computational Bio Big-Data Open Innovation Laboratory (CBBD-OIL), AIST, Shinjuku-ku, Tokyo, Japan.
| | - Takeshi Mizuguchi
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Fukuura 3-9, Kanazawa-ku, Yokohama, 236-0004, Japan
| | - Satoko Miyatake
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Fukuura 3-9, Kanazawa-ku, Yokohama, 236-0004, Japan
| | - Tomoko Toyota
- Department of Neurology, University of Occupational and Environmental Health School of Medicine, Kitakyushu, Fukuoka, Japan
| | - Hiroaki Adachi
- Department of Neurology, University of Occupational and Environmental Health School of Medicine, Kitakyushu, Fukuoka, Japan
| | - Yoko Oma
- Department of Liberal Arts, Faculty of Medicine, Saitama Medical University, Iruma, Saitama, Japan
| | - Yoshihiro Kino
- Department of Bioinformatics and Molecular Neuropathology, Meiji Pharmaceutical University, Kiyose, Tokyo, Japan
| | - Hiroaki Mitsuhashi
- Department of Applied Biochemistry, School of Engineering, Tokai University, Hiratsuka, Kanagawa, Japan
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Fukuura 3-9, Kanazawa-ku, Yokohama, 236-0004, Japan
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26
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Braz SO, Acquaire J, Gourdon G, Gomes-Pereira M. Of Mice and Men: Advances in the Understanding of Neuromuscular Aspects of Myotonic Dystrophy. Front Neurol 2018; 9:519. [PMID: 30050493 PMCID: PMC6050950 DOI: 10.3389/fneur.2018.00519] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Accepted: 06/12/2018] [Indexed: 12/26/2022] Open
Abstract
Intensive effort has been directed toward the modeling of myotonic dystrophy (DM) in mice, in order to reproduce human disease and to provide useful tools to investigate molecular and cellular pathogenesis and test efficient therapies. Mouse models have contributed to dissect the multifaceted impact of the DM mutation in various tissues, cell types and in a pleiotropy of pathways, through the expression of toxic RNA transcripts. Changes in alternative splicing, transcription, translation, intracellular RNA localization, polyadenylation, miRNA metabolism and phosphorylation of disease intermediates have been described in different tissues. Some of these events have been directly associated with specific disease symptoms in the skeletal muscle and heart of mice, offering the molecular explanation for individual disease phenotypes. In the central nervous system (CNS), however, the situation is more complex. We still do not know how the molecular abnormalities described translate into CNS dysfunction, nor do we know if the correction of individual molecular events will provide significant therapeutic benefits. The variability in model design and phenotypes described so far requires a thorough and critical analysis. In this review we discuss the recent contributions of mouse models to the understanding of neuromuscular aspects of disease, therapy development, and we provide a reflective assessment of our current limitations and pressing questions that remain unanswered.
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Affiliation(s)
- Sandra O Braz
- Laboratory CTGDM, INSERM UMR1163, Paris, France.,Institut Imagine, Université Paris Descartes-Sorbonne Paris Cité, Paris, France
| | - Julien Acquaire
- Laboratory CTGDM, INSERM UMR1163, Paris, France.,Institut Imagine, Université Paris Descartes-Sorbonne Paris Cité, Paris, France
| | - Geneviève Gourdon
- Laboratory CTGDM, INSERM UMR1163, Paris, France.,Institut Imagine, Université Paris Descartes-Sorbonne Paris Cité, Paris, France
| | - Mário Gomes-Pereira
- Laboratory CTGDM, INSERM UMR1163, Paris, France.,Institut Imagine, Université Paris Descartes-Sorbonne Paris Cité, Paris, France
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27
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Nakka K, Ghigna C, Gabellini D, Dilworth FJ. Diversification of the muscle proteome through alternative splicing. Skelet Muscle 2018; 8:8. [PMID: 29510724 PMCID: PMC5840707 DOI: 10.1186/s13395-018-0152-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 02/15/2018] [Indexed: 12/16/2022] Open
Abstract
Background Skeletal muscles express a highly specialized proteome that allows the metabolism of energy sources to mediate myofiber contraction. This muscle-specific proteome is partially derived through the muscle-specific transcription of a subset of genes. Surprisingly, RNA sequencing technologies have also revealed a significant role for muscle-specific alternative splicing in generating protein isoforms that give specialized function to the muscle proteome. Main body In this review, we discuss the current knowledge with respect to the mechanisms that allow pre-mRNA transcripts to undergo muscle-specific alternative splicing while identifying some of the key trans-acting splicing factors essential to the process. The importance of specific splicing events to specialized muscle function is presented along with examples in which dysregulated splicing contributes to myopathies. Though there is now an appreciation that alternative splicing is a major contributor to proteome diversification, the emergence of improved “targeted” proteomic methodologies for detection of specific protein isoforms will soon allow us to better appreciate the extent to which alternative splicing modifies the activity of proteins (and their ability to interact with other proteins) in the skeletal muscle. In addition, we highlight a continued need to better explore the signaling pathways that contribute to the temporal control of trans-acting splicing factor activity to ensure specific protein isoforms are expressed in the proper cellular context. Conclusions An understanding of the signal-dependent and signal-independent events driving muscle-specific alternative splicing has the potential to provide us with novel therapeutic strategies to treat different myopathies. Electronic supplementary material The online version of this article (10.1186/s13395-018-0152-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kiran Nakka
- Sprott Centre for Stem Cell Research, Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada
| | - Claudia Ghigna
- Istituto di Genetica Molecolare-Consiglio Nazionale delle Ricerche (IGM-CNR), Pavia, Italy
| | - Davide Gabellini
- Unit of Gene Expression and Muscular Dystrophy, Division of Genetics and Cell Biology, IRCCS San Raffaele Scientific Institute, DIBIT2, 5A3-44, via Olgettina 58, 20132, Milan, Italy.
| | - F Jeffrey Dilworth
- Sprott Centre for Stem Cell Research, Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada. .,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, K1H 8M5, Canada. .,Sprott Centre for Stem Cell Research, Ottawa Hospital Research Institute, 501 Smyth Rd, Mailbox 511, Ottawa, ON, K1H 8L6, Canada.
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28
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Martí E. RNA toxicity induced by expanded CAG repeats in Huntington's disease. Brain Pathol 2018; 26:779-786. [PMID: 27529325 DOI: 10.1111/bpa.12427] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 06/09/2016] [Indexed: 02/03/2023] Open
Abstract
Huntington's disease (HD) belongs to the group of inherited polyglutamine (PolyQ) diseases caused by an expanded CAG repeat in the coding region of the Huntingtin (HTT) gene that results in an elongated polyQ stretch. Abnormal function and aggregation of the mutant protein has been typically delineated as the main molecular cause underlying disease development. However, the most recent advances have revealed novel pathogenic pathways directly dependent on an RNA toxic gain-of-function. Expanded CAG repeats within exon 1 of the HTT mRNA induce toxicity through mechanisms involving, at least in part, gene expression perturbations. This has important implications not only for basic and translational research in HD, but also for other types of diseases carrying the expanded CAG in other genes, which likely share pathogenic aspects. Here I will review the evidence and mechanisms underlying RNA toxicity in CAG repeat expansions, with particular focus on HD. These comprise abnormal subcellular localization of the transcripts containing the expanded CAG repeats; sequestration of several types of proteins by the expanded CAG repeat which results in defects of alternative splicing events and gene expression; and aberrant biogenesis and detrimental activity of small CAG repeated RNAs (sCAG) that produce altered gene silencing. Although these altered pathways have been detected in HD models, their contribution to disease development and progress requires further study.
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Affiliation(s)
- Eulàlia Martí
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Dr. Aiguader 88, Barcelona, 08003, Spain.,Universitat Pompeu Fabra (UPF), Barcelona, Spain.,Institut Hospital del Mar d'Investigacions Mediques (IMIM), Barcelona, 08003, Spain.,Centro de Investigacion Biomedica en Red (CIBERESP), Madrid, Spain
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29
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Abstract
Muscleblind-like (MBNL) proteins bind to hundreds of pre- and mature mRNAs to regulate their alternative splicing, alternative polyadenylation, stability and subcellular localization. Once MBNLs are withheld from transcript regulation, cellular machineries generate products inapt for precise embryonal/adult developmental tasks and myotonic dystrophy, a devastating multi-systemic genetic disorder, develops. We have recently demonstrated that all three MBNL paralogs are capable of fine-tuning cellular content of one of the three MBNL paralogs, MBNL1, by binding to the first coding exon (e1) of its pre-mRNA. Intriguingly, this autoregulatory feedback loop grounded on alternative splicing of e1 appears to play a crucial role in delaying the onset of myotonic dystrophy. Here, we describe this process in the context of other autoregulatory and regulatory loops that maintain the content and diverse functions of MBNL proteins at optimal level in health and disease, thus supporting the overall cellular homeostasis.
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Affiliation(s)
- Patryk Konieczny
- a Department of Gene Expression , Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University , Poland
| | - Ewa Stepniak-Konieczna
- a Department of Gene Expression , Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University , Poland
| | - Krzysztof Sobczak
- a Department of Gene Expression , Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University , Poland
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30
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Sun Y, Bao Y, Han W, Song F, Shen X, Zhao J, Zuo J, Saffen D, Chen W, Wang Z, You X, Wang Y. Autoregulation of RBM10 and cross-regulation of RBM10/RBM5 via alternative splicing-coupled nonsense-mediated decay. Nucleic Acids Res 2017; 45:8524-8540. [PMID: 28586478 PMCID: PMC5737846 DOI: 10.1093/nar/gkx508] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 05/27/2017] [Indexed: 12/15/2022] Open
Abstract
Mutations in the spliceosomal RNA binding protein RBM10 cause TARP syndrome and are frequently observed in lung adenocarcinoma (LUAD). We have previously shown that RBM10 enhances exon skipping of its target genes, including its paralog RBM5. Here, we report that RBM10 negatively regulates its own mRNA and protein expression and that of RBM5 by promoting alternative splicing-coupled nonsense-mediated mRNA decay (AS-NMD). Through computational analysis and experimental validation, we identified RBM10-promoted skipping of exon 6 or 12 in RBM10 and exon 6 or 16 in RBM5 as the underlying AS-NMD events. Importantly, we showed that LUAD-associated mutations affecting splice sites of RBM10 exons 6 or 12 abolished exon inclusion and correlated with reduced expression of RBM10 RNA. Together, our investigations have revealed novel molecular mechanisms underlying RBM10 autoregulation and cross-regulation of RBM5, thereby providing insights concerning the functions of RBM10 under various physiological and pathological conditions. Our combined computational and experimental approach should be useful for elucidating the role of AS-NMD in auto- and cross-regulation by other splicing regulators.
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Affiliation(s)
- Yue Sun
- School of Life Sciences, Fudan University, Shanghai 200438, China.,Institutes of Brain Science, Fudan University, Shanghai 200032, China.,Department of Cellular and Genetic Medicine, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
| | - Yufang Bao
- Department of Cellular and Genetic Medicine, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
| | - Wenjian Han
- Key Lab of Computational Biology, CAS-MPG Partner Institute for Computational Biology, Chinese Academy of Science, Shanghai 200031, China
| | - Fan Song
- Department of Cellular and Genetic Medicine, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
| | - Xianfeng Shen
- Department of Cellular and Genetic Medicine, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
| | - Jiawei Zhao
- Department of Cellular and Genetic Medicine, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
| | - Ji Zuo
- Department of Cellular and Genetic Medicine, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
| | - David Saffen
- Institutes of Brain Science, Fudan University, Shanghai 200032, China.,Department of Cellular and Genetic Medicine, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China.,State Key Laboratory for Medical Neurobiology, Fudan University, Shanghai 200032, China
| | - Wei Chen
- Department of Biology, Southern University of Science and Technology, Shenzhen 518055, China
| | - Zefeng Wang
- Key Lab of Computational Biology, CAS-MPG Partner Institute for Computational Biology, Chinese Academy of Science, Shanghai 200031, China
| | - Xintian You
- Zuse Institute Berlin, Takustrasse 7, Berlin 14195, Germany
| | - Yongbo Wang
- Department of Cellular and Genetic Medicine, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
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31
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Konieczny P, Stepniak-Konieczna E, Taylor K, Sznajder LJ, Sobczak K. Autoregulation of MBNL1 function by exon 1 exclusion from MBNL1 transcript. Nucleic Acids Res 2017; 45:1760-1775. [PMID: 27903900 PMCID: PMC5389549 DOI: 10.1093/nar/gkw1158] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Accepted: 11/07/2016] [Indexed: 01/14/2023] Open
Abstract
Muscleblind-like proteins (MBNLs) are regulators of RNA metabolism. During tissue differentiation the level of MBNLs increases, while their functional insufficiency plays a crucial role in myotonic dystrophy (DM). Deep sequencing of RNA molecules cross-linked to immunoprecipitated protein particles (CLIP-seq) revealed that MBNL1 binds to MBNL1 exon 1 (e1) encoding both the major part of 5΄UTR and an amino-terminal region of MBNL1 protein. We tested several hypotheses regarding the possible autoregulatory function of MBNL1 binding to its own transcript. Our data indicate that MBNLs induce skipping of e1 from precursor MBNL1 mRNA and that e1 exclusion may impact transcript association with polysomes and translation. Furthermore, e1-deficient protein isoform lacking the first two zinc fingers is highly unstable and its EGFP fusion protein has severely compromised splicing activity. We also show that MBNL1 can be transcribed from three different promoters and that the transcription initiation site determines the mode of e1 regulation. Taken together, we demonstrate that MBNL proteins control steady-state levels of MBNL1 through an interaction with e1 in its precursor mRNA. Insights from our study open a new avenue in therapies against DM based on manipulation of the transcription initiation site and e1 splicing of MBNL1 mRNA.
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Affiliation(s)
- Patryk Konieczny
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
| | - Ewa Stepniak-Konieczna
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
| | - Katarzyna Taylor
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
| | - Lukasz J Sznajder
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
| | - Krzysztof Sobczak
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
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32
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Rohilla KJ, Gagnon KT. RNA biology of disease-associated microsatellite repeat expansions. Acta Neuropathol Commun 2017; 5:63. [PMID: 28851463 PMCID: PMC5574247 DOI: 10.1186/s40478-017-0468-y] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 08/22/2017] [Indexed: 12/13/2022] Open
Abstract
Microsatellites, or simple tandem repeat sequences, occur naturally in the human genome and have important roles in genome evolution and function. However, the expansion of microsatellites is associated with over two dozen neurological diseases. A common denominator among the majority of these disorders is the expression of expanded tandem repeat-containing RNA, referred to as xtrRNA in this review, which can mediate molecular disease pathology in multiple ways. This review focuses on the potential impact that simple tandem repeat expansions can have on the biology and metabolism of RNA that contain them and underscores important gaps in understanding. Merging the molecular biology of repeat expansion disorders with the current understanding of RNA biology, including splicing, transcription, transport, turnover and translation, will help clarify mechanisms of disease and improve therapeutic development.
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33
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Thornton CA, Wang E, Carrell EM. Myotonic dystrophy: approach to therapy. Curr Opin Genet Dev 2017; 44:135-140. [PMID: 28376341 PMCID: PMC5447481 DOI: 10.1016/j.gde.2017.03.007] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 02/25/2017] [Accepted: 03/13/2017] [Indexed: 01/16/2023]
Abstract
Myotonic dystrophy (DM) is a dominantly-inherited genetic disorder affecting skeletal muscle, heart, brain, and other organs. DM type 1 is caused by expansion of a CTG triplet repeat in DMPK, whereas DM type 2 is caused by expansion of a CCTG tetramer repeat in CNBP. In both cases the DM mutations lead to expression of dominant-acting RNAs. Studies of RNA toxicity have now revealed novel mechanisms and new therapeutic targets. Preclinical data have suggested that RNA dominance is responsive to therapeutic intervention and that DM therapy can be approached at several different levels. Here we review recent efforts to alleviate RNA toxicity in DM.
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Affiliation(s)
- Charles A Thornton
- Department of Neurology, University of Rochester, Rochester 14642, NY, United States.
| | - Eric Wang
- Department of Molecular Genetics & Microbiology, Center for NeuroGenetics, University of Florida, Gainesville, FL, United States
| | - Ellie M Carrell
- Department of Neurology, University of Rochester, Rochester 14642, NY, United States
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34
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Gourdon G, Meola G. Myotonic Dystrophies: State of the Art of New Therapeutic Developments for the CNS. Front Cell Neurosci 2017; 11:101. [PMID: 28473756 PMCID: PMC5397409 DOI: 10.3389/fncel.2017.00101] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 03/27/2017] [Indexed: 12/12/2022] Open
Abstract
Myotonic dystrophies are multisystemic diseases characterized not only by muscle and heart dysfunction but also by CNS alteration. They are now recognized as brain diseases affecting newborns and children for myotonic dystrophy type 1 and adults for both myotonic dystrophy type 1 and type 2. In the past two decades, much progress has been made in understanding the mechanisms underlying the DM symptoms allowing development of new molecular therapeutic tools with the ultimate aim of curing the disease. This review describes the state of the art for the characterization of CNS related symptoms, the development of molecular strategies to target the CNS as well as the available tools for screening and testing new possible treatments.
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Affiliation(s)
- Genevieve Gourdon
- Institut National de la Santé et de la Recherche Médicale UMR1163Paris, France.,Laboratory CTGDM, Institut Imagine, Université Paris Descartes-Sorbonne Paris CitéParis, France
| | - Giovanni Meola
- Department of Biomedical Sciences for Health, Policlinico San Donato (IRCCS), University of MilanMilan, Italy
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35
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Ishiguro T, Sato N, Ueyama M, Fujikake N, Sellier C, Kanegami A, Tokuda E, Zamiri B, Gall-Duncan T, Mirceta M, Furukawa Y, Yokota T, Wada K, Taylor JP, Pearson CE, Charlet-Berguerand N, Mizusawa H, Nagai Y, Ishikawa K. Regulatory Role of RNA Chaperone TDP-43 for RNA Misfolding and Repeat-Associated Translation in SCA31. Neuron 2017; 94:108-124.e7. [PMID: 28343865 PMCID: PMC5681996 DOI: 10.1016/j.neuron.2017.02.046] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 10/04/2016] [Accepted: 02/24/2017] [Indexed: 12/20/2022]
Abstract
Microsatellite expansion disorders are pathologically characterized by RNA foci formation and repeat-associated non-AUG (RAN) translation. However, their underlying pathomechanisms and regulation of RAN translation remain unknown. We report that expression of expanded UGGAA (UGGAAexp) repeats, responsible for spinocerebellar ataxia type 31 (SCA31) in Drosophila, causes neurodegeneration accompanied by accumulation of UGGAAexp RNA foci and translation of repeat-associated pentapeptide repeat (PPR) proteins, consistent with observations in SCA31 patient brains. We revealed that motor-neuron disease (MND)-linked RNA-binding proteins (RBPs), TDP-43, FUS, and hnRNPA2B1, bind to and induce structural alteration of UGGAAexp. These RBPs suppress UGGAAexp-mediated toxicity in Drosophila by functioning as RNA chaperones for proper UGGAAexp folding and regulation of PPR translation. Furthermore, nontoxic short UGGAA repeat RNA suppressed mutated RBP aggregation and toxicity in MND Drosophila models. Thus, functional crosstalk of the RNA/RBP network regulates their own quality and balance, suggesting convergence of pathomechanisms in microsatellite expansion disorders and RBP proteinopathies.
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Affiliation(s)
- Taro Ishiguro
- Department of Neurology and Neurological Science, Graduate School, Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8519, Japan; Center for Brain Integration Research (CBIR), Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8519, Japan; Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan
| | - Nozomu Sato
- Department of Neurology and Neurological Science, Graduate School, Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8519, Japan; Center for Brain Integration Research (CBIR), Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8519, Japan
| | - Morio Ueyama
- Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan; Department of Neurotherapeutics, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Nobuhiro Fujikake
- Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan
| | - Chantal Sellier
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, University of Strasbourg, Illkirch 67400, France
| | - Akemi Kanegami
- Research Institute of Biomolecule Metrology, 807-133 Enokido, Tsukuba, Ibaraki 305-0853, Japan
| | - Eiichi Tokuda
- Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Yokohama, Kanagawa 223-8522, Japan
| | - Bita Zamiri
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON M5S 3M2, Canada; Department of Genetics, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Terence Gall-Duncan
- Department of Genetics, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Program of Molecular Genetics, University of Toronto, Toronto, ON M5G 0A4, Canada
| | - Mila Mirceta
- Department of Genetics, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Program of Molecular Genetics, University of Toronto, Toronto, ON M5G 0A4, Canada
| | - Yoshiaki Furukawa
- Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Yokohama, Kanagawa 223-8522, Japan
| | - Takanori Yokota
- Department of Neurology and Neurological Science, Graduate School, Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8519, Japan; Center for Brain Integration Research (CBIR), Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8519, Japan
| | - Keiji Wada
- Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan
| | - J Paul Taylor
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Christopher E Pearson
- Department of Genetics, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Program of Molecular Genetics, University of Toronto, Toronto, ON M5G 0A4, Canada
| | - Nicolas Charlet-Berguerand
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, University of Strasbourg, Illkirch 67400, France
| | - Hidehiro Mizusawa
- Department of Neurology and Neurological Science, Graduate School, Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8519, Japan; Center for Brain Integration Research (CBIR), Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8519, Japan
| | - Yoshitaka Nagai
- Department of Degenerative Neurological Diseases, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan; Department of Neurotherapeutics, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
| | - Kinya Ishikawa
- Department of Neurology and Neurological Science, Graduate School, Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8519, Japan; Center for Brain Integration Research (CBIR), Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8519, Japan; Center for Personalized Medicine for Healthy Aging, Tokyo Medical and Dental University, Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8519, Japan.
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Zhang N, Ashizawa T. RNA toxicity and foci formation in microsatellite expansion diseases. Curr Opin Genet Dev 2017; 44:17-29. [PMID: 28208060 DOI: 10.1016/j.gde.2017.01.005] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 01/04/2017] [Accepted: 01/18/2017] [Indexed: 12/11/2022]
Abstract
More than 30 incurable neurological and neuromuscular diseases are caused by simple microsatellite expansions consisted of 3-6 nucleotides. These repeats can occur in non-coding regions and often result in a dominantly inherited disease phenotype that is characteristic of a toxic RNA gain-of-function. The expanded RNA adopts unusual secondary structures, sequesters various RNA binding proteins to form insoluble nuclear foci, and causes cellular defects at a multisystem level. Nuclear foci are dynamic in size, shape and colocalization of RNA binding proteins in different expansion diseases and tissue types. This review sets to provide new insights into the disease mechanisms of RNA toxicity and foci modulation, in light of recent advancement on bi-directional transcription, antisense RNA, repeat-associated non-ATG translation and beyond.
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Affiliation(s)
- Nan Zhang
- Neurosciences Research Program, Houston Methodist Research Institute, Houston, TX 77030, United States; Division of Cell and Molecular Biology, South Kensington Campus, Imperial College London, London SW7 2AZ, UK
| | - Tetsuo Ashizawa
- Neurosciences Research Program, Houston Methodist Research Institute, Houston, TX 77030, United States.
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Derepressing muscleblind expression by miRNA sponges ameliorates myotonic dystrophy-like phenotypes in Drosophila. Sci Rep 2016; 6:36230. [PMID: 27805016 PMCID: PMC5090246 DOI: 10.1038/srep36230] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 10/12/2016] [Indexed: 02/06/2023] Open
Abstract
Myotonic Dystrophy type 1 (DM1) originates from alleles of the DMPK gene with hundreds of extra CTG repeats in the 3′ untranslated region (3′ UTR). CUG repeat RNAs accumulate in foci that sequester Muscleblind-like (MBNL) proteins away from their functional target transcripts. Endogenous upregulation of MBNL proteins is, thus, a potential therapeutic approach to DM1. Here we identify two miRNAs, dme-miR-277 and dme-miR-304, that differentially regulate muscleblind RNA isoforms in miRNA sensor constructs. We also show that their sequestration by sponge constructs derepresses endogenous muscleblind not only in a wild type background but also in a DM1 Drosophila model expressing non-coding CUG trinucleotide repeats throughout the musculature. Enhanced muscleblind expression resulted in significant rescue of pathological phenotypes, including reversal of several mis-splicing events and reduced muscle atrophy in DM1 adult flies. Rescued flies had improved muscle function in climbing and flight assays, and had longer lifespan compared to disease controls. These studies provide proof of concept for a similar potentially therapeutic approach to DM1 in humans.
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Kino Y, Washizu C, Kurosawa M, Yamada M, Doi H, Takumi T, Adachi H, Katsuno M, Sobue G, Hicks GG, Hattori N, Shimogori T, Nukina N. FUS/TLS acts as an aggregation-dependent modifier of polyglutamine disease model mice. Sci Rep 2016; 6:35236. [PMID: 27739513 PMCID: PMC5064419 DOI: 10.1038/srep35236] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 09/26/2016] [Indexed: 12/13/2022] Open
Abstract
FUS/TLS is an RNA/DNA-binding protein associated with neurodegenerative diseases including amyotrophic lateral sclerosis and frontotemporal lobar degeneration. Previously, we found that a prion-like domain in the N-terminus of FUS/TLS mediates co-aggregation between FUS/TLS and mutant huntingtin, the gene product of Huntington's disease (HD). Here, we show that heterozygous knockout of FUS/TLS worsened the phenotypes of model mice of (HD, but not spinal and bulbar muscular atrophy (SBMA). This difference was correlated with the degree of pathological association between disease proteins and FUS/TLS. Co-aggregation between FUS/TLS and mutant huntingtin resulted in the depletion of free FUS/TLS protein in HD mice that was detected as a monomer in SDS-PAGE analysis. Recently, we found that FUS/TLS paralogs, TAF15 and EWS, were up-regulated in homozygous FUS/TLS knockout mice. These two proteins were up-regulated in both HD and FUS/TLS heterozygote mice, and were further elevated in HD-TLS+/- double mutant mice, consistent with the functional impairment of FUS/TLS. These results suggest that FUS/TLS sequestration by co-aggregation is a rate-limiting factor of disease phenotypes of HD and that inclusions may have an adverse aspect, rather than being simply benign or protective. In addition, our results highlight inclusions as repositories of potential modifiers of neurodegeneration.
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Affiliation(s)
- Yoshihiro Kino
- CREST(Core Research for Evolutionary Science and Technology), JST, Saitama, Japan.,Department of Neuroscience for Neurodegenerative Disorders, Juntendo University Graduate School of Medicine, Tokyo, Japan.,Laboratory for Structural Neuropathology , Brain Science Institute, RIKEN, Saitama, Japan.,Laboratory for Molecular Mechanisms of Thalamus Development, Brain Science Institute, RIKEN, Saitama, Japan.,Department of Bioinformatics and Molecular Neuropathology, Meiji Pharmaceutical University, Tokyo, Japan
| | - Chika Washizu
- Laboratory for Structural Neuropathology , Brain Science Institute, RIKEN, Saitama, Japan
| | - Masaru Kurosawa
- CREST(Core Research for Evolutionary Science and Technology), JST, Saitama, Japan.,Department of Neuroscience for Neurodegenerative Disorders, Juntendo University Graduate School of Medicine, Tokyo, Japan.,Laboratory for Structural Neuropathology , Brain Science Institute, RIKEN, Saitama, Japan.,Laboratory for Molecular Mechanisms of Thalamus Development, Brain Science Institute, RIKEN, Saitama, Japan
| | - Mizuki Yamada
- Laboratory for Structural Neuropathology , Brain Science Institute, RIKEN, Saitama, Japan
| | - Hiroshi Doi
- Department of Clinical Neurology and Stroke Medicine, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Toru Takumi
- CREST(Core Research for Evolutionary Science and Technology), JST, Saitama, Japan.,Laboratory for Mental Biology, Brain Science Institute, RIKEN, Saitama, Japan.,Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan
| | - Hiroaki Adachi
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Masahisa Katsuno
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Gen Sobue
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Geoffrey G Hicks
- Manitoba Institute of Cell Biology, University of Manitoba, Winnipeg, Canada
| | - Nobutaka Hattori
- Department of Neuroscience for Neurodegenerative Disorders, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Tomomi Shimogori
- Laboratory for Molecular Mechanisms of Thalamus Development, Brain Science Institute, RIKEN, Saitama, Japan
| | - Nobuyuki Nukina
- CREST(Core Research for Evolutionary Science and Technology), JST, Saitama, Japan.,Department of Neuroscience for Neurodegenerative Disorders, Juntendo University Graduate School of Medicine, Tokyo, Japan.,Laboratory for Structural Neuropathology , Brain Science Institute, RIKEN, Saitama, Japan.,Laboratory for Molecular Mechanisms of Thalamus Development, Brain Science Institute, RIKEN, Saitama, Japan.,Laboratory of Structural Neuropathology, Doshisha University Graduate School of Brain Science, Kyoto, Japan
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Sznajder ŁJ, Michalak M, Taylor K, Cywoniuk P, Kabza M, Wojtkowiak-Szlachcic A, Matłoka M, Konieczny P, Sobczak K. Mechanistic determinants of MBNL activity. Nucleic Acids Res 2016; 44:10326-10342. [PMID: 27733504 PMCID: PMC5137450 DOI: 10.1093/nar/gkw915] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 10/05/2016] [Indexed: 11/13/2022] Open
Abstract
Muscleblind-like (MBNL) proteins are critical RNA processing factors in development. MBNL activity is disrupted in the neuromuscular disease myotonic dystrophy type 1 (DM1), due to the instability of a non-coding microsatellite in the DMPK gene and the expression of CUG expansion (CUGexp) RNAs. Pathogenic interactions between MBNL and CUGexp RNA lead to the formation of nuclear complexes termed foci and prevent MBNL function in pre-mRNA processing. The existence of multiple MBNL genes, as well as multiple protein isoforms, raises the question of whether different MBNL proteins possess unique or redundant functions. To address this question, we coexpressed three MBNL paralogs in cells at equivalent levels and characterized both specific and redundant roles of these proteins in alternative splicing and RNA foci dynamics. When coexpressed in the same cells, MBNL1, MBNL2 and MBNL3 bind the same RNA motifs with different affinities. While MBNL1 demonstrated the highest splicing activity, MBNL3 showed the lowest. When forming RNA foci, MBNL1 is the most mobile paralog, while MBNL3 is rather static and the most densely packed on CUGexp RNA. Therefore, our results demonstrate that MBNL paralogs and gene-specific isoforms possess inherent functional differences, an outcome that could be enlisted to improve therapeutic strategies for DM1.
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Affiliation(s)
- Łukasz J Sznajder
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Michał Michalak
- Department of Molecular and Cellular Biology, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Katarzyna Taylor
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Piotr Cywoniuk
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Michał Kabza
- Department of Bioinformatics, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Agnieszka Wojtkowiak-Szlachcic
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Magdalena Matłoka
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Patryk Konieczny
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Krzysztof Sobczak
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
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Dose-Dependent Regulation of Alternative Splicing by MBNL Proteins Reveals Biomarkers for Myotonic Dystrophy. PLoS Genet 2016; 12:e1006316. [PMID: 27681373 PMCID: PMC5082313 DOI: 10.1371/journal.pgen.1006316] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 08/23/2016] [Indexed: 01/23/2023] Open
Abstract
Alternative splicing is a regulated process that results in expression of
specific mRNA and protein isoforms. Alternative splicing factors determine the
relative abundance of each isoform. Here we focus on MBNL1, a splicing factor
misregulated in the disease myotonic dystrophy. By altering the concentration of
MBNL1 in cells across a broad dynamic range, we show that different splicing
events require different amounts of MBNL1 for half-maximal response, and respond
more or less steeply to MBNL1. Motifs around MBNL1 exon 5 were studied to assess
how cis-elements mediate the MBNL1 dose-dependent splicing
response. A framework was developed to estimate MBNL concentration using
splicing responses alone, validated in the cell-based model, and applied to
myotonic dystrophy patient muscle. Using this framework, we evaluated the
ability of individual and combinations of splicing events to predict functional
MBNL concentration in human biopsies, as well as their performance as biomarkers
to assay mild, moderate, and severe cases of DM. Our studies provide insight into the mechanisms of myotonic dystrophy, the most
common adult form of muscular dystrophy. In this disease, a family of RNA
binding proteins is sequestered by toxic RNA, which leads to mis-regulation and
disease symptoms. We have created a cellular model with one of these family
members to study how these RNA binding proteins function in the absence of the
toxic RNA. In parallel, we analyzed transcriptomic data from over 50 individuals
(44 affected by myotonic dystrophy) with a range of disease severity. The
results from the transcriptomic data provide a rational approach to select
biomarkers for clinical research and therapeutic trials.
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Oddo JC, Saxena T, McConnell OL, Berglund JA, Wang ET. Conservation of context-dependent splicing activity in distant Muscleblind homologs. Nucleic Acids Res 2016; 44:8352-62. [PMID: 27557707 PMCID: PMC5041496 DOI: 10.1093/nar/gkw735] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 08/11/2016] [Indexed: 12/15/2022] Open
Abstract
The Muscleblind (MBL) protein family is a deeply conserved family of RNA binding proteins that regulate alternative splicing, alternative polyadenylation, RNA stability and RNA localization. Their inactivation due to sequestration by expanded CUG repeats causes symptoms in the neuromuscular disease myotonic dystrophy. MBL zinc fingers are the most highly conserved portion of these proteins, and directly interact with RNA. We identified putative MBL homologs in Ciona intestinalis and Trichoplax adhaerens, and investigated their ability, as well as that of MBL homologs from human/mouse, fly and worm, to regulate alternative splicing. We found that all homologs can regulate alternative splicing in mouse cells, with some regulating over 100 events. The cis-elements through which each homolog exerts its splicing activities are likely to be highly similar to mammalian Muscleblind-like proteins (MBNLs), as suggested by motif analyses and the ability of expanded CUG repeats to inactivate homolog-mediated splicing. While regulation of specific target exons by MBL/MBNL has not been broadly conserved across these species, genes enriched for MBL/MBNL binding sites in their introns may play roles in cell adhesion, ion transport and axon guidance, among other biological pathways, suggesting a specific, conserved role for these proteins across a broad range of metazoan species.
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Affiliation(s)
- Julia C Oddo
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Tanvi Saxena
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610, USA Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA
| | - Ona L McConnell
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610, USA Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA
| | - J Andrew Berglund
- Center for Neurogenetics, University of Florida, Gainesville, FL 32610, USA Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA Department of Chemistry and Biochemistry and Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Eric T Wang
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610, USA Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA
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Alves S, Marais T, Biferi MG, Furling D, Marinello M, El Hachimi K, Cartier N, Ruberg M, Stevanin G, Brice A, Barkats M, Sittler A. Lentiviral vector-mediated overexpression of mutant ataxin-7 recapitulates SCA7 pathology and promotes accumulation of the FUS/TLS and MBNL1 RNA-binding proteins. Mol Neurodegener 2016; 11:58. [PMID: 27465358 PMCID: PMC4964261 DOI: 10.1186/s13024-016-0123-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Accepted: 07/21/2016] [Indexed: 12/17/2022] Open
Abstract
Background We used lentiviral vectors (LVs) to generate a new SCA7 animal model overexpressing a truncated mutant ataxin-7 (MUT ATXN7) fragment in the mouse cerebellum, in order to characterize the specific neuropathological and behavioral consequences of the genetic defect in this brain structure. Results LV-mediated overexpression of MUT ATXN7 into the cerebellum of C57/BL6 adult mice induced neuropathological features similar to that observed in patients, such as intranuclear aggregates in Purkinje cells (PC), loss of synaptic markers, neuroinflammation, and neuronal death. No neuropathological changes were observed when truncated wild-type ataxin-7 (WT ATXN7) was injected. Interestingly, the local delivery of LV-expressing mutant ataxin-7 (LV-MUT-ATXN7) into the cerebellum of wild-type mice also mediated the development of an ataxic phenotype at 8 to 12 weeks post-injection. Importantly, our data revealed abnormal levels of the FUS/TLS, MBNL1, and TDP-43 RNA-binding proteins in the cerebellum of the LV-MUT-ATXN7 injected mice. MUT ATXN7 overexpression induced an increase in the levels of the pathological phosphorylated TDP-43, and a decrease in the levels of soluble FUS/TLS, with both proteins accumulating within ATXN7-positive intranuclear inclusions. MBNL1 also co-aggregated with MUT ATXN7 in most PC nuclear inclusions. Interestingly, no MBNL2 aggregation was observed in cerebellar MUT ATXN7 aggregates. Immunohistochemical studies in postmortem tissue from SCA7 patients and SCA7 knock-in mice confirmed SCA7-induced nuclear accumulation of FUS/TLS and MBNL1, strongly suggesting that these proteins play a physiopathological role in SCA7. Conclusions This study validates a novel SCA7 mouse model based on lentiviral vectors, in which strong and sustained expression of MUT ATXN7 in the cerebellum was found sufficient to generate motor defects. Electronic supplementary material The online version of this article (doi:10.1186/s13024-016-0123-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sandro Alves
- INSERM U 1127, CNRS UMR 7225, Sorbonne Universités UPMC, Univ Paris 06 UMR_S 1127, ICM (Brain and Spine Institute) Pitié-Salpêtrière Hospital, 75013, Paris, France.
| | - Thibaut Marais
- CNRS FRE3617, Center for Research in Myology, Sorbonne Universités UPMC Univ Paris 06, INSERM UMRS974, Institut de Myologie, G-H Pitié-Salpêtrière, 75013, Paris, France
| | - Maria-Grazia Biferi
- CNRS FRE3617, Center for Research in Myology, Sorbonne Universités UPMC Univ Paris 06, INSERM UMRS974, Institut de Myologie, G-H Pitié-Salpêtrière, 75013, Paris, France
| | - Denis Furling
- CNRS FRE3617, Center for Research in Myology, Sorbonne Universités UPMC Univ Paris 06, INSERM UMRS974, Institut de Myologie, G-H Pitié-Salpêtrière, 75013, Paris, France
| | - Martina Marinello
- INSERM U 1127, CNRS UMR 7225, Sorbonne Universités UPMC, Univ Paris 06 UMR_S 1127, ICM (Brain and Spine Institute) Pitié-Salpêtrière Hospital, 75013, Paris, France.,EPHE Ecole Pratique des Hautes Etudes, Laboratoire de Neurogénétique, PSL Universités, 75013, Paris, France
| | - Khalid El Hachimi
- INSERM U 1127, CNRS UMR 7225, Sorbonne Universités UPMC, Univ Paris 06 UMR_S 1127, ICM (Brain and Spine Institute) Pitié-Salpêtrière Hospital, 75013, Paris, France.,EPHE Ecole Pratique des Hautes Etudes, Laboratoire de Neurogénétique, PSL Universités, 75013, Paris, France
| | | | - Merle Ruberg
- INSERM U 1127, CNRS UMR 7225, Sorbonne Universités UPMC, Univ Paris 06 UMR_S 1127, ICM (Brain and Spine Institute) Pitié-Salpêtrière Hospital, 75013, Paris, France
| | - Giovanni Stevanin
- INSERM U 1127, CNRS UMR 7225, Sorbonne Universités UPMC, Univ Paris 06 UMR_S 1127, ICM (Brain and Spine Institute) Pitié-Salpêtrière Hospital, 75013, Paris, France.,EPHE Ecole Pratique des Hautes Etudes, Laboratoire de Neurogénétique, PSL Universités, 75013, Paris, France.,Département de Génétique et Cytogénétique, AP-HP, G-H Pitié-Salpêtrière, 47 Bd de l'Hôpital, 75013, Paris, France
| | - Alexis Brice
- INSERM U 1127, CNRS UMR 7225, Sorbonne Universités UPMC, Univ Paris 06 UMR_S 1127, ICM (Brain and Spine Institute) Pitié-Salpêtrière Hospital, 75013, Paris, France.,Département de Génétique et Cytogénétique, AP-HP, G-H Pitié-Salpêtrière, 47 Bd de l'Hôpital, 75013, Paris, France
| | - Martine Barkats
- CNRS FRE3617, Center for Research in Myology, Sorbonne Universités UPMC Univ Paris 06, INSERM UMRS974, Institut de Myologie, G-H Pitié-Salpêtrière, 75013, Paris, France
| | - Annie Sittler
- INSERM U 1127, CNRS UMR 7225, Sorbonne Universités UPMC, Univ Paris 06 UMR_S 1127, ICM (Brain and Spine Institute) Pitié-Salpêtrière Hospital, 75013, Paris, France.
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Coram RJ, Stillwagon SJ, Guggilam A, Jenkins MW, Swanson MS, Ladd AN. Muscleblind-like 1 is required for normal heart valve development in vivo. BMC DEVELOPMENTAL BIOLOGY 2015; 15:36. [PMID: 26472242 PMCID: PMC4608261 DOI: 10.1186/s12861-015-0087-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 10/09/2015] [Indexed: 12/26/2022]
Abstract
Background Development of the valves and septa of the heart depends on the formation and remodeling of the endocardial cushions in the atrioventricular canal and outflow tract. These cushions are populated by mesenchyme produced from the endocardium by epithelial-mesenchymal transition (EMT). The endocardial cushions are remodeled into the valves at post-EMT stages via differentiation of the mesenchyme and changes in the extracellular matrix (ECM). Transforming growth factor β (TGFβ) signaling has been implicated in both the induction of EMT in the endocardial cushions and the remodeling of the valves at post-EMT stages. We previously identified the RNA binding protein muscleblind-like 1 (MBNL1) as a negative regulator of TGFβ signaling and EMT in chicken endocardial cushions ex vivo. Here, we investigate the role of MBNL1 in endocardial cushion development and valvulogenesis in Mbnl1∆E3/∆E3 mice, which are null for MBNL1 protein. Methods Collagen gel invasion assays, histology, immunohistochemistry, real-time RT-PCR, optical coherence tomography, and echocardiography were used to evaluate EMT and TGFβ signaling in the endocardial cushions, and morphogenesis, ECM composition, and function of the heart valves. Results As in chicken, the loss of MBNL1 promotes precocious TGFβ signaling and EMT in the endocardial cushions. Surprisingly, this does not lead to the production of excess mesenchyme, but later valve morphogenesis is aberrant. Adult Mbnl1∆E3/∆E3 mice exhibit valve dysmorphia with elevated TGFβ signaling, changes in ECM composition, and increased pigmentation. This is accompanied by a high incidence of regurgitation across both inflow and outflow valves. Mbnl1∆E3/∆E3 mice also have a high incidence of ostium secundum septal defects accompanied by atrial communication, but do not develop overt cardiomyopathy. Conclusions Together, these data indicate that MBNL1 plays a conserved role in negatively regulating TGFβ signaling, and is required for normal valve morphogenesis and homeostasis in vivo. Electronic supplementary material The online version of this article (doi:10.1186/s12861-015-0087-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ryan J Coram
- Department of Cellular & Molecular Medicine, Lerner Research Institute, 9500 Euclid Ave. NC10, Cleveland Clinic, Cleveland, OH, 44195, USA. .,Present Address: Ohio University Heritage College of Osteopathic Medicine, Athens, OH, 45701, USA.
| | - Samantha J Stillwagon
- Department of Cellular & Molecular Medicine, Lerner Research Institute, 9500 Euclid Ave. NC10, Cleveland Clinic, Cleveland, OH, 44195, USA. .,Present Address: Department of Obstetrics and Gynecology, Women's Health Institute, Cleveland Clinic, Cleveland, OH, 44195, USA.
| | - Anuradha Guggilam
- Department of Cellular & Molecular Medicine, Lerner Research Institute, 9500 Euclid Ave. NC10, Cleveland Clinic, Cleveland, OH, 44195, USA.
| | - Michael W Jenkins
- Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA.
| | - Maurice S Swanson
- Department of Molecular Genetics & Microbiology, College of Medicine, Center for NeuroGenetics and the Genetics Institute, University of Florida, Gainesville, FL, 32610, USA.
| | - Andrea N Ladd
- Department of Cellular & Molecular Medicine, Lerner Research Institute, 9500 Euclid Ave. NC10, Cleveland Clinic, Cleveland, OH, 44195, USA.
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Goodwin M, Mohan A, Batra R, Lee KY, Charizanis K, Fernández Gómez FJ, Eddarkaoui S, Sergeant N, Buée L, Kimura T, Clark HB, Dalton J, Takamura K, Weyn-Vanhentenryck SM, Zhang C, Reid T, Ranum LPW, Day JW, Swanson MS. MBNL Sequestration by Toxic RNAs and RNA Misprocessing in the Myotonic Dystrophy Brain. Cell Rep 2015; 12:1159-68. [PMID: 26257173 DOI: 10.1016/j.celrep.2015.07.029] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 06/24/2015] [Accepted: 07/14/2015] [Indexed: 11/19/2022] Open
Abstract
For some neurological disorders, disease is primarily RNA mediated due to expression of non-coding microsatellite expansion RNAs (RNA(exp)). Toxicity is thought to result from enhanced binding of proteins to these expansions and depletion from their normal cellular targets. However, experimental evidence for this sequestration model is lacking. Here, we use HITS-CLIP and pre-mRNA processing analysis of human control versus myotonic dystrophy (DM) brains to provide compelling evidence for this RNA toxicity model. MBNL2 binds directly to DM repeat expansions in the brain, resulting in depletion from its normal RNA targets with downstream effects on alternative splicing and polyadenylation. Similar RNA processing defects were detected in Mbnl compound-knockout mice, highlighted by dysregulation of Mapt splicing and fetal tau isoform expression in adults. These results demonstrate that MBNL proteins are directly sequestered by RNA(exp) in the DM brain and introduce a powerful experimental tool to evaluate RNA-mediated toxicity in other expansion diseases.
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Affiliation(s)
- Marianne Goodwin
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Apoorva Mohan
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Ranjan Batra
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Kuang-Yung Lee
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA; Department of Neurology, Chang Gung Memorial Hospital, Keelung 20401, Taiwan
| | - Konstantinos Charizanis
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA; InSiliGen LLC, Gainesville, FL 32606, USA
| | - Francisco José Fernández Gómez
- Inserm UMR S1172, Alzheimer and Tauopathies, Université Lille Nord de France, Centre Jean-Pierre Aubert, 1 Place Verdun, 59045 Lille, France
| | - Sabiha Eddarkaoui
- Inserm UMR S1172, Alzheimer and Tauopathies, Université Lille Nord de France, Centre Jean-Pierre Aubert, 1 Place Verdun, 59045 Lille, France
| | - Nicolas Sergeant
- Inserm UMR S1172, Alzheimer and Tauopathies, Université Lille Nord de France, Centre Jean-Pierre Aubert, 1 Place Verdun, 59045 Lille, France
| | - Luc Buée
- Inserm UMR S1172, Alzheimer and Tauopathies, Université Lille Nord de France, Centre Jean-Pierre Aubert, 1 Place Verdun, 59045 Lille, France
| | - Takashi Kimura
- Division of Neurology, Department of Internal Medicine, Hyogo College of Medicine, Hyogo 663-8501, Japan
| | - H Brent Clark
- Departments of Laboratory Medicine and Pathology, Neurology, Neurosurgery, and Genetics, Cell Biology, and Development, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Joline Dalton
- Departments of Laboratory Medicine and Pathology, Neurology, Neurosurgery, and Genetics, Cell Biology, and Development, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Kenji Takamura
- Departments of Laboratory Medicine and Pathology, Neurology, Neurosurgery, and Genetics, Cell Biology, and Development, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Sebastien M Weyn-Vanhentenryck
- Department of Systems Biology, Department of Biochemistry and Molecular Biophysics, Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA
| | - Chaolin Zhang
- Department of Systems Biology, Department of Biochemistry and Molecular Biophysics, Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA
| | - Tammy Reid
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Laura P W Ranum
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - John W Day
- Department of Neurology and Neurological Sciences, School of Medicine, Stanford University, Palo Alto, CA 94305, USA
| | - Maurice S Swanson
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA.
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Sun X, Li PP, Zhu S, Cohen R, Marque LO, Ross CA, Pulst SM, Chan HYE, Margolis RL, Rudnicki DD. Nuclear retention of full-length HTT RNA is mediated by splicing factors MBNL1 and U2AF65. Sci Rep 2015. [PMID: 26218986 PMCID: PMC4517393 DOI: 10.1038/srep12521] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Huntington's disease (HD) is caused by a CAG repeat expansion in the huntingtin (HTT) gene. Recent evidence suggests that HD is a consequence of multimodal, non-mutually exclusive mechanisms of pathogenesis that involve both HTT protein- and HTT RNA-triggered mechanisms. Here we provide further evidence for the role of expanded HTT (expHTT) RNA in HD by demonstrating that a fragment of expHTT is cytotoxic in the absence of any translation and that the extent of cytotoxicity is similar to the cytotoxicity of an expHTT protein fragment encoded by a transcript of similar length and with a similar repeat size. In addition, full-length (FL) expHTT is retained in the nucleus. Overexpression of the splicing factor muscleblind-like 1 (MBNL1) increases nuclear retention of expHTT and decreases the expression of expHTT protein in the cytosol. The splicing and nuclear export factor U2AF65 has the opposite effect, decreasing expHTT nuclear retention and increasing expression of expHTT protein. This suggests that MBNL1 and U2AF65 play a role in nuclear export of expHTT RNA.
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Affiliation(s)
- Xin Sun
- 1] Department of Psychiatry and Behavioral Sciences, Division of Neurobiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA [2] Guangdong-Hong Kong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, Guangdong, China
| | - Pan P Li
- Department of Psychiatry and Behavioral Sciences, Division of Neurobiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Shanshan Zhu
- Department of Psychiatry and Behavioral Sciences, Division of Neurobiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Rachael Cohen
- Department of Psychiatry and Behavioral Sciences, Division of Neurobiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Leonard O Marque
- Department of Psychiatry and Behavioral Sciences, Division of Neurobiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Christopher A Ross
- 1] Department of Psychiatry and Behavioral Sciences, Division of Neurobiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA [2] Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA [3] Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA [4] Program of Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Stefan M Pulst
- Department of Neurology, University of Utah, Salt Lake City, Utah, USA
| | - Ho Yin Edwin Chan
- Laboratory of Drosophila Research, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - Russell L Margolis
- 1] Department of Psychiatry and Behavioral Sciences, Division of Neurobiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA [2] Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA [3] Program of Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Dobrila D Rudnicki
- 1] Department of Psychiatry and Behavioral Sciences, Division of Neurobiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA [2] Program of Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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