1
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Almeida CF, Robriquet F, Vetter TA, Huang N, Neinast R, Hernandez-Rosario L, Rajakumar D, Arnold WD, McBride KL, Flanigan KM, Weiss RB, Wein N. Promising AAV.U7snRNAs vectors targeting DMPK improve DM1 hallmarks in patient-derived cell lines. Front Cell Dev Biol 2023; 11:1181040. [PMID: 37397246 PMCID: PMC10309041 DOI: 10.3389/fcell.2023.1181040] [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: 03/06/2023] [Accepted: 05/18/2023] [Indexed: 07/04/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) is the most common form of muscular dystrophy in adults and affects mainly the skeletal muscle, heart, and brain. DM1 is caused by a CTG repeat expansion in the 3'UTR region of the DMPK gene that sequesters muscleblind-like proteins, blocking their splicing activity and forming nuclear RNA foci. Consequently, many genes have their splicing reversed to a fetal pattern. There is no treatment for DM1, but several approaches have been explored, including antisense oligonucleotides (ASOs) aiming to knock down DMPK expression or bind to the CTGs expansion. ASOs were shown to reduce RNA foci and restore the splicing pattern. However, ASOs have several limitations and although being safe treated DM1 patients did not demonstrate improvement in a human clinical trial. AAV-based gene therapies have the potential to overcome such limitations, providing longer and more stable expression of antisense sequences. In the present study, we designed different antisense sequences targeting exons 5 or 8 of DMPK and the CTG repeat tract aiming to knock down DMPK expression or promote steric hindrance, respectively. The antisense sequences were inserted in U7snRNAs, which were then vectorized in AAV8 particles. Patient-derived myoblasts treated with AAV8. U7snRNAs showed a significant reduction in the number of RNA foci and re-localization of muscle-blind protein. RNA-seq analysis revealed a global splicing correction in different patient-cell lines, without alteration in DMPK expression.
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Affiliation(s)
- Camila F. Almeida
- Center for Gene Therapy, Nationwide Children’s Hospital, Columbus, OH, United States
| | - Florence Robriquet
- Center for Gene Therapy, Nationwide Children’s Hospital, Columbus, OH, United States
| | - Tatyana A. Vetter
- Center for Gene Therapy, Nationwide Children’s Hospital, Columbus, OH, United States
| | - Nianyuan Huang
- Center for Gene Therapy, Nationwide Children’s Hospital, Columbus, OH, United States
| | - Reid Neinast
- Center for Cardiovascular Research, Nationwide Children’s Hospital, Columbus, OH, United States
| | | | - Dhanarajan Rajakumar
- Center for Gene Therapy, Nationwide Children’s Hospital, Columbus, OH, United States
| | - W. David Arnold
- Department of Neurology, The Ohio State University, Columbus, OH, United States
- Department of Physical Medicine and Rehabilitation, University of Missouri School of Medicine, Columbia, MO, United States
| | - Kim L. McBride
- Center for Cardiovascular Research, Nationwide Children’s Hospital, Columbus, OH, United States
- Department of Medical Genetics, University of Calgary, Calgary, AB, Canada
| | - Kevin M. Flanigan
- Center for Gene Therapy, Nationwide Children’s Hospital, Columbus, OH, United States
- Department of Neurology, The Ohio State University, Columbus, OH, United States
- Department of Pediatrics, The Ohio State University, Columbus, OH, United States
| | - Robert B. Weiss
- Department of Human Genetics, The University of Utah School of Medicine, Salt Lake City, UT, United States
| | - Nicolas Wein
- Center for Gene Therapy, Nationwide Children’s Hospital, Columbus, OH, United States
- Department of Pediatrics, The Ohio State University, Columbus, OH, United States
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2
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Pascual-Gilabert M, Artero R, López-Castel A. The myotonic dystrophy type 1 drug development pipeline: 2022 edition. Drug Discov Today 2023; 28:103489. [PMID: 36634841 DOI: 10.1016/j.drudis.2023.103489] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 12/23/2022] [Accepted: 01/04/2023] [Indexed: 01/11/2023]
Abstract
The beginning of the 20th decade has witnessed an increase in drug development programs for myotonic dystrophy type 1 (DM1). We have collected nearly 20 candidate drugs with accomplished preclinical and clinical phases, updating our previous drug development pipeline review with new entries and relevant milestones for pre-existing candidates. Three interventional first-in-human clinical trials got underway with distinct drug classes, namely AOC 1001 and DYNE-101 nucleic acid-based therapies, and the small molecule pitolisant, which joins the race toward market authorization with other repurposed drugs, including tideglusib, metformin, or mexiletine, already in clinical evaluation. Furthermore, newly disclosed promising preclinical data for several additional nucleic-acid therapeutic candidates and a CRISPR-based approach, as well as the advent into the pipeline of novel therapeutic programs, increase the plausibility of success in the demanding task of providing valid treatments to patients with DM1.
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Affiliation(s)
| | - Ruben Artero
- University Institute for Biotechnology and Biomedicine (BIOTECMED), University of Valencia, Valencia, Spain; Translational Genomics Group, Incliva Biomedical Research Institute, Valencia, Spain.
| | - Arturo López-Castel
- University Institute for Biotechnology and Biomedicine (BIOTECMED), University of Valencia, Valencia, Spain; Translational Genomics Group, Incliva Biomedical Research Institute, Valencia, Spain.
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3
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Pluripotent Stem Cells in Disease Modeling and Drug Discovery for Myotonic Dystrophy Type 1. Cells 2023; 12:cells12040571. [PMID: 36831237 PMCID: PMC9954118 DOI: 10.3390/cells12040571] [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: 01/10/2023] [Revised: 02/04/2023] [Accepted: 02/07/2023] [Indexed: 02/12/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a progressive multisystemic disease caused by the expansion of a CTG repeat tract within the 3' untranslated region (3' UTR) of the dystrophia myotonica protein kinase gene (DMPK). Although DM1 is considered to be the most frequent myopathy of genetic origin in adults, DM1 patients exhibit a vast diversity of symptoms, affecting many different organs. Up until now, different in vitro models from patients' derived cells have largely contributed to the current understanding of DM1. Most of those studies have focused on muscle physiopathology. However, regarding the multisystemic aspect of DM1, there is still a crucial need for relevant cellular models to cover the whole complexity of the disease and open up options for new therapeutic approaches. This review discusses how human pluripotent stem cell-based models significantly contributed to DM1 mechanism decoding, and how they provided new therapeutic strategies that led to actual phase III clinical trials.
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4
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Faber GP, Nadav-Eliyahu S, Shav-Tal Y. Nuclear speckles - a driving force in gene expression. J Cell Sci 2022; 135:275909. [PMID: 35788677 DOI: 10.1242/jcs.259594] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Nuclear speckles are dynamic membraneless bodies located in the cell nucleus. They harbor RNAs and proteins, many of which are splicing factors, that together display complex biophysical properties dictating nuclear speckle formation and maintenance. Although these nuclear bodies were discovered decades ago, only recently has in-depth genomic analysis begun to unravel their essential functions in modulation of gene activity. Major advancements in genomic mapping techniques combined with microscopy approaches have enabled insights into the roles nuclear speckles may play in enhancing gene expression, and how gene positioning to specific nuclear landmarks can regulate gene expression and RNA processing. Some studies have drawn a link between nuclear speckles and disease. Certain maladies either involve nuclear speckles directly or dictate the localization and reorganization of many nuclear speckle factors. This is most striking during viral infection, as viruses alter the entire nuclear architecture and highjack host machinery. As discussed in this Review, nuclear speckles represent a fascinating target of study not only to reveal the links between gene positioning, genome subcompartments and gene activity, but also as a potential target for therapeutics.
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Affiliation(s)
- Gabriel P Faber
- The Mina and Everard Goodman Faculty of Life Sciences , Bar-Ilan University, Ramat Gan 5290002, Israel.,Institute of Nanotechnology , Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Shani Nadav-Eliyahu
- The Mina and Everard Goodman Faculty of Life Sciences , Bar-Ilan University, Ramat Gan 5290002, Israel.,Institute of Nanotechnology , Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Yaron Shav-Tal
- The Mina and Everard Goodman Faculty of Life Sciences , Bar-Ilan University, Ramat Gan 5290002, Israel.,Institute of Nanotechnology , Bar-Ilan University, Ramat Gan 5290002, Israel
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5
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Gulyurtlu S, Magon MS, Guest P, Papavasiliou PP, Morrison KD, Prescott AR, Sleeman JE. Condensation properties of stress granules and processing bodies are compromised in Myotonic Dystrophy Type 1. Dis Model Mech 2022; 15:276177. [PMID: 35642886 PMCID: PMC9366894 DOI: 10.1242/dmm.049294] [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: 09/08/2021] [Accepted: 05/23/2022] [Indexed: 11/26/2022] Open
Abstract
RNA regulation in mammalian cells requires complex physical compartmentalisation, using structures thought to be formed by liquid-liquid phase separation. Disruption of these structures is implicated in numerous degenerative diseases. Myotonic dystrophy type 1 (DM1) is a multi-systemic trinucleotide repeat disorder resulting from an expansion of nucleotides CTG (CTGexp) in the DNA encoding DM1 protein kinase (DMPK). The cellular hallmark of DM1 is the formation of nuclear foci that contain expanded DMPK RNA (CUGexp) (with thymine instead of uracil). We report here the deregulation of stress granules (SGs) and processing bodies (P-bodies), two cytoplasmic structures key for mRNA regulation, in cell culture models of DM1. Alterations to the rates of formation and dispersal of SGs suggest an altered ability of cells to respond to stress associated with DM1, while changes to the structure and dynamics of SGs and P-bodies suggest that a widespread alteration to the biophysical properties of cellular structures is a consequence of the presence of CUGexp RNA. Summary: Validation of an inducible model of myotonic dystrophy type 1 that shows altered cellular stress responses. These involve phase-separated cellular structures also implicated in other degenerative conditions.
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Affiliation(s)
- Selma Gulyurtlu
- Biomolecular Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST, UK
| | - Monika S Magon
- Biomolecular Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST, UK
| | - Patrick Guest
- Biomolecular Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST, UK
| | - Panagiotis P Papavasiliou
- Biomolecular Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST, UK
| | - Kim D Morrison
- Biomolecular Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST, UK
| | - Alan R Prescott
- School of Life Science, University of Dundee, Dundee, DD1 5EH, UK
| | - Judith E Sleeman
- Biomolecular Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST, UK
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6
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Overby SJ, Cerro-Herreros E, González-Martínez I, Varela MA, Seoane-Miraz D, Jad Y, Raz R, Møller T, Pérez-Alonso M, Wood MJ, Llamusí B, Artero R. Proof of concept of peptide-linked blockmiR-induced MBNL functional rescue in myotonic dystrophy type 1 mouse model. MOLECULAR THERAPY. NUCLEIC ACIDS 2022; 27:1146-1155. [PMID: 35282418 PMCID: PMC8888893 DOI: 10.1016/j.omtn.2022.02.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 02/06/2022] [Indexed: 01/25/2023]
Abstract
Myotonic dystrophy type 1 is a debilitating neuromuscular disease causing muscle weakness, myotonia, and cardiac dysfunction. The phenotypes are caused by muscleblind-like (MBNL) protein sequestration by toxic RNA in the DM1 protein kinase (DMPK) gene. DM1 patients exhibit a pathogenic number of repetitions in DMPK, which leads to downstream symptoms. Another disease characteristic is altered microRNA (miRNA) expression. It was previously shown that miR-23b regulates the translation of MBNL1 into protein. Antisense oligonucleotide (AON) treatment targeting this miRNA can improve disease symptoms. Here, we present a refinement of this strategy targeting a miR-23b binding site on the MBNL1 3' UTR in DM1 model cells and mice by using AONs called blockmiRs. BlockmiRs linked to novel cell-penetrating peptide chemistry showed an increase in MBNL1 protein in DM1 model cells and HSALR mice. They also showed an increase in muscle strength and significant rescue of downstream splicing and histological phenotypes in mice without disturbing the endogenous levels of other miR-23b target transcripts.
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Affiliation(s)
- Sarah J Overby
- University Institute of Biotechnology and Biomedicine (BIOTECMED), Universidad de Valencia, 46100 Burjassot, Spain.,Translational Genomics Group, Incliva Biomedical Research Institute, 46010 Valencia, Spain
| | - Estefanía Cerro-Herreros
- University Institute of Biotechnology and Biomedicine (BIOTECMED), Universidad de Valencia, 46100 Burjassot, Spain.,Translational Genomics Group, Incliva Biomedical Research Institute, 46010 Valencia, Spain
| | - Irene González-Martínez
- University Institute of Biotechnology and Biomedicine (BIOTECMED), Universidad de Valencia, 46100 Burjassot, Spain.,Translational Genomics Group, Incliva Biomedical Research Institute, 46010 Valencia, Spain
| | - Miguel A Varela
- Department of Paediatrics, University of Oxford, John Radcliffe Hospital, OX3 9DU Oxford, UK.,MDUK Oxford Neuromuscular Centre, University of Oxford, Oxford, UK
| | - David Seoane-Miraz
- Department of Paediatrics, University of Oxford, John Radcliffe Hospital, OX3 9DU Oxford, UK.,MDUK Oxford Neuromuscular Centre, University of Oxford, Oxford, UK
| | - Yahya Jad
- Department of Paediatrics, University of Oxford, John Radcliffe Hospital, OX3 9DU Oxford, UK.,MDUK Oxford Neuromuscular Centre, University of Oxford, Oxford, UK
| | - Richard Raz
- Department of Paediatrics, University of Oxford, John Radcliffe Hospital, OX3 9DU Oxford, UK.,MDUK Oxford Neuromuscular Centre, University of Oxford, Oxford, UK
| | | | - Manuel Pérez-Alonso
- University Institute of Biotechnology and Biomedicine (BIOTECMED), Universidad de Valencia, 46100 Burjassot, Spain.,Translational Genomics Group, Incliva Biomedical Research Institute, 46010 Valencia, Spain
| | - Matthew J Wood
- Department of Paediatrics, University of Oxford, John Radcliffe Hospital, OX3 9DU Oxford, UK.,MDUK Oxford Neuromuscular Centre, University of Oxford, Oxford, UK
| | - Beatriz Llamusí
- University Institute of Biotechnology and Biomedicine (BIOTECMED), Universidad de Valencia, 46100 Burjassot, Spain.,Translational Genomics Group, Incliva Biomedical Research Institute, 46010 Valencia, Spain
| | - Rubén Artero
- University Institute of Biotechnology and Biomedicine (BIOTECMED), Universidad de Valencia, 46100 Burjassot, Spain.,Translational Genomics Group, Incliva Biomedical Research Institute, 46010 Valencia, Spain
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7
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Dastidar S, Majumdar D, Tipanee J, Singh K, Klein AF, Furling D, Chuah MK, VandenDriessche T. Comprehensive transcriptome-wide analysis of spliceopathy correction of myotonic dystrophy using CRISPR-Cas9 in iPSCs-derived cardiomyocytes. Mol Ther 2022; 30:75-91. [PMID: 34371182 PMCID: PMC8753376 DOI: 10.1016/j.ymthe.2021.08.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 07/01/2021] [Accepted: 07/26/2021] [Indexed: 01/07/2023] Open
Abstract
CTG repeat expansion (CTGexp) is associated with aberrant alternate splicing that contributes to cardiac dysfunction in myotonic dystrophy type 1 (DM1). Excision of this CTGexp repeat using CRISPR-Cas resulted in the disappearance of punctate ribonuclear foci in cardiomyocyte-like cells derived from DM1-induced pluripotent stem cells (iPSCs). This was associated with correction of the underlying spliceopathy as determined by RNA sequencing and alternate splicing analysis. Certain genes were of particular interest due to their role in cardiac development, maturation, and function (TPM4, CYP2J2, DMD, MBNL3, CACNA1H, ROCK2, ACTB) or their association with splicing (SMN2, GCFC2, MBNL3). Moreover, while comparing isogenic CRISPR-Cas9-corrected versus non-corrected DM1 cardiomyocytes, a prominent difference in the splicing pattern for a number of candidate genes was apparent pertaining to genes that are associated with cardiac function (TNNT, TNNT2, TTN, TPM1, SYNE1, CACNA1A, MTMR1, NEBL, TPM1), cellular signaling (NCOR2, CLIP1, LRRFIP2, CLASP1, CAMK2G), and other DM1-related genes (i.e., NUMA1, MBNL2, LDB3) in addition to the disease-causing DMPK gene itself. Subsequent validation using a selected gene subset, including MBNL1, MBNL2, INSR, ADD3, and CRTC2, further confirmed correction of the spliceopathy following CTGexp repeat excision. To our knowledge, the present study provides the first comprehensive unbiased transcriptome-wide analysis of the differential splicing landscape in DM1 patient-derived cardiac cells after excision of the CTGexp repeat using CRISPR-Cas9, showing reversal of the abnormal cardiac spliceopathy in DM1.
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Affiliation(s)
- Sumitava Dastidar
- Department of Gene Therapy & Regenerative Medicine, Vrije Universiteit Brussel, 1090 Brussels, Belgium
| | - Debanjana Majumdar
- Department of Gene Therapy & Regenerative Medicine, Vrije Universiteit Brussel, 1090 Brussels, Belgium
| | - Jaitip Tipanee
- Department of Gene Therapy & Regenerative Medicine, Vrije Universiteit Brussel, 1090 Brussels, Belgium
| | - Kshitiz Singh
- Department of Gene Therapy & Regenerative Medicine, Vrije Universiteit Brussel, 1090 Brussels, Belgium
| | - Arnaud F. Klein
- Sorbonne Université, Inserm, Institut de Myologie, Centre de Recherche en Myologie, F-75013 Paris, France
| | - Denis Furling
- Sorbonne Université, Inserm, Institut de Myologie, Centre de Recherche en Myologie, F-75013 Paris, France
| | - Marinee K. Chuah
- Department of Gene Therapy & Regenerative Medicine, Vrije Universiteit Brussel, 1090 Brussels, Belgium,Center for Molecular & Vascular Biology, Department of Cardiovascular Sciences, University of Leuven, 3000 Leuven, Belgium,Corresponding author: Marinee K. Chuah, Department of Gene Therapy & Regenerative Medicine, Vrije Universiteit Brussel, 1090 Brussels, Belgium.
| | - Thierry VandenDriessche
- Department of Gene Therapy & Regenerative Medicine, Vrije Universiteit Brussel, 1090 Brussels, Belgium,Center for Molecular & Vascular Biology, Department of Cardiovascular Sciences, University of Leuven, 3000 Leuven, Belgium,Corresponding author: Thierry VandenDriessche, Department of Gene Therapy & Regenerative Medicine, Vrije Universiteit Brussel, 1090 Brussels, Belgium.
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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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Cerro-Herreros E, González-Martínez I, Moreno N, Espinosa-Espinosa J, Fernández-Costa JM, Colom-Rodrigo A, Overby SJ, Seoane-Miraz D, Poyatos-García J, Vilchez JJ, López de Munain A, Varela MA, Wood MJ, Pérez-Alonso M, Llamusí B, Artero R. Preclinical characterization of antagomiR-218 as a potential treatment for myotonic dystrophy. MOLECULAR THERAPY. NUCLEIC ACIDS 2021; 26:174-191. [PMID: 34513303 PMCID: PMC8413838 DOI: 10.1016/j.omtn.2021.07.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Accepted: 07/17/2021] [Indexed: 12/13/2022]
Abstract
Myotonic dystrophy type 1 (DM1) is a rare neuromuscular disease caused by expansion of unstable CTG repeats in a non-coding region of the DMPK gene. CUG expansions in mutant DMPK transcripts sequester MBNL1 proteins in ribonuclear foci. Depletion of this protein is a primary contributor to disease symptoms such as muscle weakness and atrophy and myotonia, yet upregulation of endogenous MBNL1 levels may compensate for this sequestration. Having previously demonstrated that antisense oligonucleotides against miR-218 boost MBNL1 expression and rescue phenotypes in disease models, here we provide preclinical characterization of an antagomiR-218 molecule using the HSALR mouse model and patient-derived myotubes. In HSALR, antagomiR-218 reached 40–60 pM 2 weeks after injection, rescued molecular and functional phenotypes in a dose- and time-dependent manner, and showed a good toxicity profile after a single subcutaneous administration. In muscle tissue, antagomiR rescued the normal subcellular distribution of Mbnl1 and did not alter the proportion of myonuclei containing CUG foci. In patient-derived cells, antagomiR-218 improved defective fusion and differentiation and rescued up to 34% of the gene expression alterations found in the transcriptome of patient cells. Importantly, miR-218 was found to be upregulated in DM1 muscle biopsies, pinpointing this microRNA (miRNA) as a relevant therapeutic target.
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Affiliation(s)
- Estefanía Cerro-Herreros
- University Research Institute for Biotechnology and Biomedicine (BIOTECMED), Universidad de Valencia, Dr. Moliner, 50, 46100 Burjasot, Valencia, Spain.,Incliva Biomedical Research Institute, Avenida Menéndez Pelayo 4 acc, 46010 Valencia, Spain
| | - Irene González-Martínez
- University Research Institute for Biotechnology and Biomedicine (BIOTECMED), Universidad de Valencia, Dr. Moliner, 50, 46100 Burjasot, Valencia, Spain.,Incliva Biomedical Research Institute, Avenida Menéndez Pelayo 4 acc, 46010 Valencia, Spain
| | - Nerea Moreno
- University Research Institute for Biotechnology and Biomedicine (BIOTECMED), Universidad de Valencia, Dr. Moliner, 50, 46100 Burjasot, Valencia, Spain.,Incliva Biomedical Research Institute, Avenida Menéndez Pelayo 4 acc, 46010 Valencia, Spain
| | - Jorge Espinosa-Espinosa
- University Research Institute for Biotechnology and Biomedicine (BIOTECMED), Universidad de Valencia, Dr. Moliner, 50, 46100 Burjasot, Valencia, Spain.,Incliva Biomedical Research Institute, Avenida Menéndez Pelayo 4 acc, 46010 Valencia, Spain
| | - Juan M Fernández-Costa
- University Research Institute for Biotechnology and Biomedicine (BIOTECMED), Universidad de Valencia, Dr. Moliner, 50, 46100 Burjasot, Valencia, Spain.,Incliva Biomedical Research Institute, Avenida Menéndez Pelayo 4 acc, 46010 Valencia, Spain
| | - Anna Colom-Rodrigo
- University Research Institute for Biotechnology and Biomedicine (BIOTECMED), Universidad de Valencia, Dr. Moliner, 50, 46100 Burjasot, Valencia, Spain.,Incliva Biomedical Research Institute, Avenida Menéndez Pelayo 4 acc, 46010 Valencia, Spain
| | - Sarah J Overby
- University Research Institute for Biotechnology and Biomedicine (BIOTECMED), Universidad de Valencia, Dr. Moliner, 50, 46100 Burjasot, Valencia, Spain.,Incliva Biomedical Research Institute, Avenida Menéndez Pelayo 4 acc, 46010 Valencia, Spain
| | - David Seoane-Miraz
- Department of Paediatrics, University of Oxford, John Radcliffe Hospital, Headley Way, OX3 9DU, Oxford, UK.,MDUK Oxford Neuromuscular Centre, University of Oxford, Oxford, UK
| | - Javier Poyatos-García
- The IISLAFE Health Research Institute, Avenida Fernando Abril Martorell, 106 Torre A 7 planta, 46026 Valencia, Spain.,Neuromuscular Reference Centre ERN EURO-NMD and Neuromuscular Pathology and Ataxia Research Group, Hospital La Fe Health Research Institute, Valencia, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Juan J Vilchez
- The IISLAFE Health Research Institute, Avenida Fernando Abril Martorell, 106 Torre A 7 planta, 46026 Valencia, Spain.,Neuromuscular Reference Centre ERN EURO-NMD and Neuromuscular Pathology and Ataxia Research Group, Hospital La Fe Health Research Institute, Valencia, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Adolfo López de Munain
- Biodonostia Health Research Institute, P° Dr. Beguiristain s/n, 20014 Donostia-San Sebastián, Spain.,Hospital Universitario Donostia-Osakidetza-Departamento de Neurociencias-Universidad del Pais Vasco-CIBERNED
| | - Miguel A Varela
- Department of Paediatrics, University of Oxford, John Radcliffe Hospital, Headley Way, OX3 9DU, Oxford, UK.,MDUK Oxford Neuromuscular Centre, University of Oxford, Oxford, UK
| | - Matthew J Wood
- Department of Paediatrics, University of Oxford, John Radcliffe Hospital, Headley Way, OX3 9DU, Oxford, UK.,MDUK Oxford Neuromuscular Centre, University of Oxford, Oxford, UK
| | - Manuel Pérez-Alonso
- University Research Institute for Biotechnology and Biomedicine (BIOTECMED), Universidad de Valencia, Dr. Moliner, 50, 46100 Burjasot, Valencia, Spain.,Incliva Biomedical Research Institute, Avenida Menéndez Pelayo 4 acc, 46010 Valencia, Spain
| | - Beatriz Llamusí
- University Research Institute for Biotechnology and Biomedicine (BIOTECMED), Universidad de Valencia, Dr. Moliner, 50, 46100 Burjasot, Valencia, Spain.,Incliva Biomedical Research Institute, Avenida Menéndez Pelayo 4 acc, 46010 Valencia, Spain
| | - Rubén Artero
- University Research Institute for Biotechnology and Biomedicine (BIOTECMED), Universidad de Valencia, Dr. Moliner, 50, 46100 Burjasot, Valencia, Spain.,Incliva Biomedical Research Institute, Avenida Menéndez Pelayo 4 acc, 46010 Valencia, Spain
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10
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Ketley A, Wojciechowska M, Ghidelli-Disse S, Bamborough P, Ghosh TK, Morato ML, Sedehizadeh S, Malik NA, Tang Z, Powalowska P, Tanner M, Billeter-Clark R, Trueman RC, Geiszler PC, Agostini A, Othman O, Bösche M, Bantscheff M, Rüdiger M, Mossakowska DE, Drewry DH, Zuercher WJ, Thornton CA, Drewes G, Uings I, Hayes CJ, Brook JD. CDK12 inhibition reduces abnormalities in cells from patients with myotonic dystrophy and in a mouse model. Sci Transl Med 2021; 12:12/541/eaaz2415. [PMID: 32350131 DOI: 10.1126/scitranslmed.aaz2415] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 09/16/2019] [Accepted: 02/25/2020] [Indexed: 12/17/2022]
Abstract
Myotonic dystrophy type 1 (DM1) is an RNA-based disease with no current treatment. It is caused by a transcribed CTG repeat expansion within the 3' untranslated region of the dystrophia myotonica protein kinase (DMPK) gene. Mutant repeat expansion transcripts remain in the nuclei of patients' cells, forming distinct microscopically detectable foci that contribute substantially to the pathophysiology of the condition. Here, we report small-molecule inhibitors that remove nuclear foci and have beneficial effects in the HSALR mouse model, reducing transgene expression, leading to improvements in myotonia, splicing, and centralized nuclei. Using chemoproteomics in combination with cell-based assays, we identify cyclin-dependent kinase 12 (CDK12) as a druggable target for this condition. CDK12 is a protein elevated in DM1 cell lines and patient muscle biopsies, and our results showed that its inhibition led to reduced expression of repeat expansion RNA. Some of the inhibitors identified in this study are currently the subject of clinical trials for other indications and provide valuable starting points for a drug development program in DM1.
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Affiliation(s)
- Ami Ketley
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Marzena Wojciechowska
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Sonja Ghidelli-Disse
- Cellzome GmbH, Molecular Discovery Research, GlaxoSmithKline, Meyerhofstrasse 1, 61997 Heidelberg, Germany
| | - Paul Bamborough
- Computational and Modelling Sciences, GlaxoSmithKline, Medicines Research Centre, Hertfordshire SG1 2NY, UK
| | - Tushar K Ghosh
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Marta Lopez Morato
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Saam Sedehizadeh
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Naveed Altaf Malik
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Zhenzhi Tang
- Department of Neurology, University of Rochester Medical Center, Rochester, NY 14642-0001, USA
| | - Paulina Powalowska
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK.,School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Matthew Tanner
- Department of Neurology, University of Rochester Medical Center, Rochester, NY 14642-0001, USA
| | - Rudolf Billeter-Clark
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Rebecca C Trueman
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Philippine C Geiszler
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Alessandra Agostini
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Othman Othman
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Markus Bösche
- Cellzome GmbH, Molecular Discovery Research, GlaxoSmithKline, Meyerhofstrasse 1, 61997 Heidelberg, Germany
| | - Marcus Bantscheff
- Cellzome GmbH, Molecular Discovery Research, GlaxoSmithKline, Meyerhofstrasse 1, 61997 Heidelberg, Germany
| | - Martin Rüdiger
- Screening Profiling and Mechanistic Biology, GlaxoSmithKline, Medicines Research Centre, Hertfordshire SG1 2NY, UK
| | - Danuta E Mossakowska
- Discovery Partnerships with Academia, GlaxoSmithKline, Medicines Research Centre, Hertfordshire SG1 2NY, UK.,Malopolska Centre of Biotechnology, Jagiellonian University, 30-348 Krakow, Poland
| | - David H Drewry
- Department of Chemical Biology, GlaxoSmithKline, Research Triangle Park, NC 27709-3398, USA
| | - William J Zuercher
- Department of Chemical Biology, GlaxoSmithKline, Research Triangle Park, NC 27709-3398, USA.,SGC Center for Chemical Biology, UNC, Eshelman School of Pharmacy, Chapel Hill, NC 27599, USA
| | - Charles A Thornton
- Department of Neurology, University of Rochester Medical Center, Rochester, NY 14642-0001, USA
| | - Gerard Drewes
- Cellzome GmbH, Molecular Discovery Research, GlaxoSmithKline, Meyerhofstrasse 1, 61997 Heidelberg, Germany
| | - Iain Uings
- Discovery Partnerships with Academia, GlaxoSmithKline, Medicines Research Centre, Hertfordshire SG1 2NY, UK
| | - Christopher J Hayes
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - J David Brook
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK.
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11
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Liao SE, Regev O. Splicing at the phase-separated nuclear speckle interface: a model. Nucleic Acids Res 2021; 49:636-645. [PMID: 33337476 PMCID: PMC7826271 DOI: 10.1093/nar/gkaa1209] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 11/24/2020] [Accepted: 12/03/2020] [Indexed: 02/07/2023] Open
Abstract
Phase-separated membraneless bodies play important roles in nucleic acid biology. While current models for the roles of phase separation largely focus on the compartmentalization of constituent proteins, we reason that other properties of phase separation may play functional roles. Specifically, we propose that interfaces of phase-separated membraneless bodies could have functional roles in spatially organizing biochemical reactions. Here we propose such a model for the nuclear speckle, a membraneless body implicated in RNA splicing. In our model, sequence-dependent RNA positioning along the nuclear speckle interface coordinates RNA splicing. Our model asserts that exons are preferentially sequestered into nuclear speckles through binding by SR proteins, while introns are excluded through binding by nucleoplasmic hnRNP proteins. As a result, splice sites at exon-intron boundaries are preferentially positioned at nuclear speckle interfaces. This positioning exposes splice sites to interface-localized spliceosomes, enabling the subsequent splicing reaction. Our model provides a simple mechanism that seamlessly explains much of the complex logic of splicing. This logic includes experimental results such as the antagonistic duality between splicing factors, the position dependence of splicing sequence motifs, and the collective contribution of many motifs to splicing decisions. Similar functional roles for phase-separated interfaces may exist for other membraneless bodies.
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Affiliation(s)
- Susan E Liao
- Computer Science Department, Courant Institute of Mathematical Sciences, New York University, New York, NY, USA
| | - Oded Regev
- Computer Science Department, Courant Institute of Mathematical Sciences, New York University, New York, NY, USA
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12
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Johnson SJ, Cooper TA. Overlapping mechanisms of lncRNA and expanded microsatellite RNA. WILEY INTERDISCIPLINARY REVIEWS. RNA 2021; 12:e1634. [PMID: 33191580 PMCID: PMC7880542 DOI: 10.1002/wrna.1634] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 10/14/2020] [Accepted: 10/20/2020] [Indexed: 12/15/2022]
Abstract
RNA has major regulatory roles in a wide range of biological processes and a surge of RNA research has led to the classification of numerous functional RNA species. One example is long noncoding RNAs (lncRNAs) that are structurally complex transcripts >200 nucleotides (nt) in length and lacking a canonical open reading frame (ORF). Despite a general lack of sequence conservation and low expression levels, many lncRNAs have been shown to have functionality in diverse biological processes as well as in mechanisms of disease. In parallel with the growing understanding of lncRNA functions, there is a growing subset of microsatellite expansion disorders in which the primary mechanism of pathogenesis is an RNA gain of function arising from RNA transcripts from the mutant allele. Microsatellite expansion disorders are caused by an expansion of short (3-10 nt) repeats located within coding genes. Expanded repeat-containing RNA mediates toxicity through multiple mechanisms, the details of which remain only partially understood. The purpose of this review is to highlight the links between functional mechanisms of lncRNAs and the potential pathogenic mechanisms of expanded microsatellite RNA. These shared mechanisms include protein sequestration, peptide translation, micro-RNA (miRNA) processing, and miRNA sequestration. Recognizing the parallels between the normal functions of lncRNAs and the negative impact of expanded microsatellite RNA on biological processes can provide reciprocal understanding to the roles of both RNA species. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications RNA in Disease and Development > RNA in Disease.
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Affiliation(s)
- Sara J Johnson
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Thomas A Cooper
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, USA
- Department of Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, USA
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13
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First Identification of RNA-Binding Proteins That Regulate Alternative Exons in the Dystrophin Gene. Int J Mol Sci 2020; 21:ijms21207803. [PMID: 33096920 PMCID: PMC7589424 DOI: 10.3390/ijms21207803] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 10/16/2020] [Accepted: 10/19/2020] [Indexed: 12/29/2022] Open
Abstract
The Duchenne muscular dystrophy (DMD) gene has a complex expression pattern regulated by multiple tissue-specific promoters and by alternative splicing (AS) of the resulting transcripts. Here, we used an RNAi-based approach coupled with DMD-targeted RNA-seq to identify RNA-binding proteins (RBPs) that regulate splicing of its skeletal muscle isoform (Dp427m) in a human muscular cell line. A total of 16 RBPs comprising the major regulators of muscle-specific splicing events were tested. We show that distinct combinations of RBPs maintain the correct inclusion in the Dp427m of exons that undergo spatio-temporal AS in other dystrophin isoforms. In particular, our findings revealed the complex networks of RBPs contributing to the splicing of the two short DMD exons 71 and 78, the inclusion of exon 78 in the adult Dp427m isoform being crucial for muscle function. Among the RBPs tested, QKI and DDX5/DDX17 proteins are important determinants of DMD exon inclusion. This is the first large-scale study to determine which RBP proteins act on the physiological splicing of the DMD gene. Our data shed light on molecular mechanisms contributing to the expression of the different dystrophin isoforms, which could be influenced by a change in the function or expression level of the identified RBPs.
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14
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An Overview of Alternative Splicing Defects Implicated in Myotonic Dystrophy Type I. Genes (Basel) 2020; 11:genes11091109. [PMID: 32971903 PMCID: PMC7564762 DOI: 10.3390/genes11091109] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 09/14/2020] [Accepted: 09/17/2020] [Indexed: 01/02/2023] Open
Abstract
Myotonic dystrophy type I (DM1) is the most common form of adult muscular dystrophy, caused by expansion of a CTG triplet repeat in the 3′ untranslated region (3′UTR) of the myotonic dystrophy protein kinase (DMPK) gene. The pathological CTG repeats result in protein trapping by expanded transcripts, a decreased DMPK translation and the disruption of the chromatin structure, affecting neighboring genes expression. The muscleblind-like (MBNL) and CUG-BP and ETR-3-like factors (CELF) are two families of tissue-specific regulators of developmentally programmed alternative splicing that act as antagonist regulators of several pre-mRNA targets, including troponin 2 (TNNT2), insulin receptor (INSR), chloride channel 1 (CLCN1) and MBNL2. Sequestration of MBNL proteins and up-regulation of CELF1 are key to DM1 pathology, inducing a spliceopathy that leads to a developmental remodelling of the transcriptome due to an adult-to-foetal splicing switch, which results in the loss of cell function and viability. Moreover, recent studies indicate that additional pathogenic mechanisms may also contribute to disease pathology, including a misregulation of cellular mRNA translation, localization and stability. This review focuses on the cause and effects of MBNL and CELF1 deregulation in DM1, describing the molecular mechanisms underlying alternative splicing misregulation for a deeper understanding of DM1 complexity. To contribute to this analysis, we have prepared a comprehensive list of transcript alterations involved in DM1 pathogenesis, as well as other deregulated mRNA processing pathways implications.
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15
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Benhamou RI, Vezina-Dawod S, Choudhary S, Won Wang K, Meyer SM, Yildirim I, Disney MD. Macrocyclization of a Ligand Targeting a Toxic RNA Dramatically Improves Potency. Chembiochem 2020; 21:3229-3233. [PMID: 32649032 DOI: 10.1002/cbic.202000445] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Indexed: 12/21/2022]
Abstract
RNA molecules both contribute to and are causative of many human diseases. One method to perturb RNA function is to target its structure with small molecules. However, discovering bioactive ligands for RNA targets is challenging. Here, we show that the bioactivity of a linear dimeric ligand that inactivates the RNA trinucleotide repeat expansion that causes myotonic dystrophy type 1 [DM1; r(CUG)exp ] can be improved by macrocyclization. Indeed, the macrocyclic compound is ten times more potent than the linear compound for improving DM1-associated defects in cells, including in patient-derived myotubes (muscle cells). This enhancement in potency is due to the macrocycle's increased affinity and selectively for the target, which inhibit r(CUG)exp 's toxic interaction with muscleblind-like 1 (MBNL1), and its superior cell permeability. Macrocyclization could prove to be an effective way to enhance the bioactivity of modularly assembled ligands targeting RNA.
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Affiliation(s)
- Raphael I Benhamou
- Departments of Chemistry and Neuroscience, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA
| | - Simon Vezina-Dawod
- Departments of Chemistry and Neuroscience, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA
| | - Shruti Choudhary
- Departments of Chemistry and Neuroscience, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA
| | - Kye Won Wang
- Department of Chemistry, Florida Atlantic University, John D. MacArthur Campus, Jupiter, FL 33458, USA
| | - Samantha M Meyer
- Departments of Chemistry and Neuroscience, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA
| | - Ilyas Yildirim
- Department of Chemistry, Florida Atlantic University, John D. MacArthur Campus, Jupiter, FL 33458, USA
| | - Matthew D Disney
- Departments of Chemistry and Neuroscience, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA
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16
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Fischer S, Di Liddo A, Taylor K, Gerhardus JS, Sobczak K, Zarnack K, Weigand JE. Muscleblind-like 2 controls the hypoxia response of cancer cells. RNA (NEW YORK, N.Y.) 2020; 26:648-663. [PMID: 32127384 PMCID: PMC7161353 DOI: 10.1261/rna.073353.119] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 02/27/2020] [Indexed: 05/03/2023]
Abstract
Hypoxia is a hallmark of solid cancers, supporting proliferation, angiogenesis, and escape from apoptosis. There is still limited understanding of how cancer cells adapt to hypoxic conditions and survive. We analyzed transcriptome changes of human lung and breast cancer cells under chronic hypoxia. Hypoxia induced highly concordant changes in transcript abundance, but divergent splicing responses, underlining the cell type-specificity of alternative splicing programs. While RNA-binding proteins were predominantly reduced, hypoxia specifically induced muscleblind-like protein 2 (MBNL2). Strikingly, MBNL2 induction was critical for hypoxia adaptation by controlling the transcript abundance of hypoxia response genes, such as vascular endothelial growth factor A (VEGFA) MBNL2 depletion reduced the proliferation and migration of cancer cells, demonstrating an important role of MBNL2 as cancer driver. Hypoxia control is specific for MBNL2 and not shared by its paralog MBNL1. Thus, our study revealed MBNL2 as central mediator of cancer cell responses to hypoxia, regulating the expression and alternative splicing of hypoxia-induced genes.
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Affiliation(s)
- Sandra Fischer
- Department of Biology, Technical University of Darmstadt, Darmstadt, 64287, Germany
| | - Antonella Di Liddo
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt am Main, 60438, Germany
| | - Katarzyna Taylor
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Poznan, 61-614, Poland
| | - Jamina S Gerhardus
- Department of Biology, Technical University of Darmstadt, Darmstadt, 64287, Germany
| | - Krzysztof Sobczak
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Poznan, 61-614, Poland
| | - Kathi Zarnack
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt am Main, 60438, Germany
| | - Julia E Weigand
- Department of Biology, Technical University of Darmstadt, Darmstadt, 64287, Germany
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17
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Benhamou RI, Angelbello AJ, Andrews RJ, Wang ET, Moss WN, Disney MD. Structure-Specific Cleavage of an RNA Repeat Expansion with a Dimeric Small Molecule Is Advantageous over Sequence-Specific Recognition by an Oligonucleotide. ACS Chem Biol 2020; 15:485-493. [PMID: 31927948 DOI: 10.1021/acschembio.9b00958] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Myotonic dystrophy type 2 (DM2) is a genetically defined muscular dystrophy that is caused by an expanded repeat of r(CCUG) [r(CCUG)exp] in intron 1 of a CHC-type zinc finger nucleic acid binding protein (CNBP) pre-mRNA. Various mechanisms contribute to DM2 pathology including pre-mRNA splicing defects caused by sequestration of the RNA splicing regulator muscleblind-like-1 (MBNL1) by r(CCUG)exp. Herein, we study the biological impacts of the molecular recognition of r(CCUG)exp's structure by a designer dimeric small molecule that directly cleaves the RNA in patient-derived cells. The compound is comprised of two RNA-binding modules conjugated to a derivative of the natural product bleomycin. Careful design of the chimera affords RNA-specific cleavage, as attachment of the bleomycin cleaving module was done in a manner that disables DNA cleavage. The chimeric cleaver is more potent than the parent binding compound for alleviating DM2-associated defects. Importantly, oligonucleotides targeting the r(CCUG)exp sequence for cleavage exacerbate DM2 defects due to recognition of a short r(CCUG) sequence that is embedded in CNBP, argonaute-1 (AGO1), and MBNL1, reducing their levels. The latter event causes a greater depletion of functional MBNL1 than the amount already sequestered by r(CCUG)exp. Thus, compounds targeting RNA structures can have functional advantages over oligonucleotides that target the sequence in some disease settings, particularly in DM2.
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Affiliation(s)
- Raphael I. Benhamou
- Department of Chemistry, The Scripps Research Institute, 110 Scripps Way, Jupiter, Florida 33458, United States
| | - Alicia J. Angelbello
- Department of Chemistry, The Scripps Research Institute, 110 Scripps Way, Jupiter, Florida 33458, United States
| | - Ryan J. Andrews
- Roy J. Carver Department of Biophysics, Biochemistry, and Molecular Biology, Iowa State University, Ames, Iowa 50011, United States
| | - Eric T. Wang
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics, UF Genetics Institute, University of Florida, 2033 Mowry Road, Gainesville, Florida 32610, United States
| | - Walter N. Moss
- Roy J. Carver Department of Biophysics, Biochemistry, and Molecular Biology, Iowa State University, Ames, Iowa 50011, United States
| | - Matthew D. Disney
- Department of Chemistry, The Scripps Research Institute, 110 Scripps Way, Jupiter, Florida 33458, United States
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18
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Dastidar S, Ardui S, Singh K, Majumdar D, Nair N, Fu Y, Reyon D, Samara E, Gerli MF, Klein AF, De Schrijver W, Tipanee J, Seneca S, Tulalamba W, Wang H, Chai Y, In’t Veld P, Furling D, Tedesco F, Vermeesch JR, Joung JK, Chuah MK, VandenDriessche T. Efficient CRISPR/Cas9-mediated editing of trinucleotide repeat expansion in myotonic dystrophy patient-derived iPS and myogenic cells. Nucleic Acids Res 2018; 46:8275-8298. [PMID: 29947794 PMCID: PMC6144820 DOI: 10.1093/nar/gky548] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 06/01/2018] [Accepted: 06/05/2018] [Indexed: 12/17/2022] Open
Abstract
CRISPR/Cas9 is an attractive platform to potentially correct dominant genetic diseases by gene editing with unprecedented precision. In the current proof-of-principle study, we explored the use of CRISPR/Cas9 for gene-editing in myotonic dystrophy type-1 (DM1), an autosomal-dominant muscle disorder, by excising the CTG-repeat expansion in the 3'-untranslated-region (UTR) of the human myotonic dystrophy protein kinase (DMPK) gene in DM1 patient-specific induced pluripotent stem cells (DM1-iPSC), DM1-iPSC-derived myogenic cells and DM1 patient-specific myoblasts. To eliminate the pathogenic gain-of-function mutant DMPK transcript, we designed a dual guide RNA based strategy that excises the CTG-repeat expansion with high efficiency, as confirmed by Southern blot and single molecule real-time (SMRT) sequencing. Correction efficiencies up to 90% could be attained in DM1-iPSC as confirmed at the clonal level, following ribonucleoprotein (RNP) transfection of CRISPR/Cas9 components without the need for selective enrichment. Expanded CTG repeat excision resulted in the disappearance of ribonuclear foci, a quintessential cellular phenotype of DM1, in the corrected DM1-iPSC, DM1-iPSC-derived myogenic cells and DM1 myoblasts. Consequently, the normal intracellular localization of the muscleblind-like splicing regulator 1 (MBNL1) was restored, resulting in the normalization of splicing pattern of SERCA1. This study validates the use of CRISPR/Cas9 for gene editing of repeat expansions.
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Affiliation(s)
- Sumitava Dastidar
- Department of Gene Therapy & Regenerative Medicine, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Simon Ardui
- Department of Human Genetics, University of Leuven, Leuven 3000, Belgium
| | - Kshitiz Singh
- Department of Gene Therapy & Regenerative Medicine, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Debanjana Majumdar
- Department of Gene Therapy & Regenerative Medicine, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Nisha Nair
- Department of Gene Therapy & Regenerative Medicine, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Yanfang Fu
- Molecular Pathology Unit, Center for Cancer Research and Center for Computational and Integrative Biology, Massachusetts General Hospital, Charlestown, MA02129, USA
- Department of Pathology, Harvard Medical School, Boston, MA 02115, USA
| | - Deepak Reyon
- Molecular Pathology Unit, Center for Cancer Research and Center for Computational and Integrative Biology, Massachusetts General Hospital, Charlestown, MA02129, USA
- Department of Pathology, Harvard Medical School, Boston, MA 02115, USA
| | - Ermira Samara
- Department of Gene Therapy & Regenerative Medicine, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Mattia F M Gerli
- Department of Cell and Developmental Biology, University College London, London WC1E6DE, UK
| | - Arnaud F Klein
- Sorbonne Universités, INSERM, Association Institute de Myologie, Center de Recherche en Myologie, F-75013 , France
| | - Wito De Schrijver
- Department of Gene Therapy & Regenerative Medicine, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Jaitip Tipanee
- Department of Gene Therapy & Regenerative Medicine, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Sara Seneca
- Research Group Reproduction and Genetics (REGE), Center for Medical Genetics, UZ Brussels, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Warut Tulalamba
- Department of Gene Therapy & Regenerative Medicine, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Hui Wang
- Department of Gene Therapy & Regenerative Medicine, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Yoke Chin Chai
- Department of Gene Therapy & Regenerative Medicine, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Peter In’t Veld
- Department of Pathology, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Denis Furling
- Sorbonne Universités, INSERM, Association Institute de Myologie, Center de Recherche en Myologie, F-75013 , France
| | | | - Joris R Vermeesch
- Department of Human Genetics, University of Leuven, Leuven 3000, Belgium
| | - J Keith Joung
- Molecular Pathology Unit, Center for Cancer Research and Center for Computational and Integrative Biology, Massachusetts General Hospital, Charlestown, MA02129, USA
- Department of Pathology, Harvard Medical School, Boston, MA 02115, USA
| | - Marinee K Chuah
- Department of Gene Therapy & Regenerative Medicine, Vrije Universiteit Brussel, Brussels 1090, Belgium
- Center for Molecular & Vascular Biology, Department of Cardiovascular Sciences, University of Leuven, Leuven 3000, Belgium
| | - Thierry VandenDriessche
- Department of Gene Therapy & Regenerative Medicine, Vrije Universiteit Brussel, Brussels 1090, Belgium
- Center for Molecular & Vascular Biology, Department of Cardiovascular Sciences, University of Leuven, Leuven 3000, Belgium
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19
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Matloka M, Klein AF, Rau F, Furling D. Cells of Matter- In Vitro Models for Myotonic Dystrophy. Front Neurol 2018; 9:361. [PMID: 29875732 PMCID: PMC5974047 DOI: 10.3389/fneur.2018.00361] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 05/03/2018] [Indexed: 12/17/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1 also known as Steinert disease) is a multisystemic disorder mainly characterized by myotonia, progressive muscle weakness and wasting, cognitive impairments, and cardiac defects. This autosomal dominant disease is caused by the expression of nuclear retained RNAs containing pathologic expanded CUG repeats that alter the function of RNA-binding proteins in a tissue-specific manner, leading ultimately to neuromuscular dysfunction and clinical symptoms. Although considerable knowledge has been gathered on myotonic dystrophy since its first description, the development of novel relevant disease models remains of high importance to investigate pathophysiologic mechanisms and to assess new therapeutic approaches. In addition to animal models, in vitro cell cultures provide a unique resource for both fundamental and translational research. This review discusses how cellular models broke ground to decipher molecular basis of DM1 and describes currently available cell models, ranging from exogenous expression of the CTG tracts to variable patients' derived cells.
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Affiliation(s)
| | | | | | - Denis Furling
- Sorbonne Université, INSERM, Association Institut de Myologie, Centre de Recherche en Myologie, Paris, France
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20
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López-Morató M, Brook JD, Wojciechowska M. Small Molecules Which Improve Pathogenesis of Myotonic Dystrophy Type 1. Front Neurol 2018; 9:349. [PMID: 29867749 PMCID: PMC5968088 DOI: 10.3389/fneur.2018.00349] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 04/30/2018] [Indexed: 12/30/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is the most common muscular dystrophy in adults for which there is currently no treatment. The pathogenesis of this autosomal dominant disorder is associated with the expansion of CTG repeats in the 3'-UTR of the DMPK gene. DMPK transcripts with expanded CUG repeats (CUGexpDMPK) are retained in the nucleus forming multiple discrete foci, and their presence triggers a cascade of toxic events. Thus far, most research emphasis has been on interactions of CUGexpDMPK with the muscleblind-like (MBNL) family of splicing factors. These proteins are sequestered by the expanded CUG repeats of DMPK RNA leading to their functional depletion. As a consequence, abnormalities in many pathways of RNA metabolism, including alternative splicing, are detected in DM1. To date, in vitro and in vivo efforts to develop therapeutic strategies for DM1 have mostly been focused on targeting CUGexpDMPK via reducing their expression and/or preventing interactions with MBNL1. Antisense oligonucleotides targeted to the CUG repeats in the DMPK transcripts are of particular interest due to their potential capacity to discriminate between mutant and normal transcripts. However, a growing number of reports describe alternative strategies using small molecule chemicals acting independently of a direct interaction with CUGexpDMPK. In this review, we summarize current knowledge about these chemicals and we describe the beneficial effects they caused in different DM1 experimental models. We also present potential mechanisms of action of these compounds and pathways they affect which could be considered for future therapeutic interventions in DM1.
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Affiliation(s)
- Marta López-Morató
- Queen’s Medical Centre, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - John David Brook
- Queen’s Medical Centre, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Marzena Wojciechowska
- Queen’s Medical Centre, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
- Polish Academy of Sciences, Department of Molecular Genetics, Institute of Bioorganic Chemistry, Poznan, Poland
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21
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Deregulation of RNA Metabolism in Microsatellite Expansion Diseases. ADVANCES IN NEUROBIOLOGY 2018; 20:213-238. [PMID: 29916021 DOI: 10.1007/978-3-319-89689-2_8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
RNA metabolism impacts different steps of mRNA life cycle including splicing, polyadenylation, nucleo-cytoplasmic export, translation, and decay. Growing evidence indicates that defects in any of these steps lead to devastating diseases in humans. This chapter reviews the various RNA metabolic mechanisms that are disrupted in Myotonic Dystrophy-a trinucleotide repeat expansion disease-due to dysregulation of RNA-Binding Proteins. We also compare Myotonic Dystrophy to other microsatellite expansion disorders and describe how some of these mechanisms commonly exert direct versus indirect effects toward disease pathologies.
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22
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Galganski L, Urbanek MO, Krzyzosiak WJ. Nuclear speckles: molecular organization, biological function and role in disease. Nucleic Acids Res 2017; 45:10350-10368. [PMID: 28977640 PMCID: PMC5737799 DOI: 10.1093/nar/gkx759] [Citation(s) in RCA: 285] [Impact Index Per Article: 40.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 08/18/2017] [Indexed: 12/13/2022] Open
Abstract
The nucleoplasm is not homogenous; it consists of many types of nuclear bodies, also known as nuclear domains or nuclear subcompartments. These self-organizing structures gather machinery involved in various nuclear activities. Nuclear speckles (NSs) or splicing speckles, also called interchromatin granule clusters, were discovered as sites for splicing factor storage and modification. Further studies on transcription and mRNA maturation and export revealed a more general role for splicing speckles in RNA metabolism. Here, we discuss the functional implications of the localization of numerous proteins crucial for epigenetic regulation, chromatin organization, DNA repair and RNA modification to nuclear speckles. We highlight recent advances suggesting that NSs facilitate integrated regulation of gene expression. In addition, we consider the influence of abundant regulatory and signaling proteins, i.e. protein kinases and proteins involved in protein ubiquitination, phosphoinositide signaling and nucleoskeletal organization, on pre-mRNA synthesis and maturation. While many of these regulatory proteins act within NSs, direct evidence for mRNA metabolism events occurring in NSs is still lacking. NSs contribute to numerous human diseases, including cancers and viral infections. In addition, recent data have demonstrated close relationships between these structures and the development of neurological disorders.
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Affiliation(s)
- Lukasz Galganski
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
| | - Martyna O Urbanek
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
| | - Wlodzimierz J Krzyzosiak
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
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23
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Provenzano C, Cappella M, Valaperta R, Cardani R, Meola G, Martelli F, Cardinali B, Falcone G. CRISPR/Cas9-Mediated Deletion of CTG Expansions Recovers Normal Phenotype in Myogenic Cells Derived from Myotonic Dystrophy 1 Patients. MOLECULAR THERAPY-NUCLEIC ACIDS 2017; 9:337-348. [PMID: 29246312 PMCID: PMC5684470 DOI: 10.1016/j.omtn.2017.10.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 10/11/2017] [Accepted: 10/11/2017] [Indexed: 02/05/2023]
Abstract
Myotonic dystrophy type 1 (DM1) is the most common adult-onset muscular dystrophy, characterized by progressive myopathy, myotonia, and multi-organ involvement. This dystrophy is an inherited autosomal dominant disease caused by a (CTG)n expansion within the 3′ untranslated region of the DMPK gene. Expression of the mutated gene results in production of toxic transcripts that aggregate as nuclear foci and sequester RNA-binding proteins, resulting in mis-splicing of several transcripts, defective translation, and microRNA dysregulation. No effective therapy is yet available for treatment of the disease. In this study, myogenic cell models were generated from myotonic dystrophy patient-derived fibroblasts. These cells exhibit typical disease-associated ribonuclear aggregates, containing CUG repeats and muscleblind-like 1 protein, and alternative splicing alterations. We exploited these cell models to develop new gene therapy strategies aimed at eliminating the toxic mutant repeats. Using the CRISPR/Cas9 gene-editing system, the repeat expansions were removed, therefore preventing nuclear foci formation and splicing alterations. Compared with the previously reported strategies of inhibition/degradation of CUG expanded transcripts by various techniques, the advantage of this approach is that affected cells can be permanently reverted to a normal phenotype.
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Affiliation(s)
- Claudia Provenzano
- Institute of Cell Biology and Neurobiology, National Research Council, Monterotondo, Rome, Italy
| | - Marisa Cappella
- Institute of Cell Biology and Neurobiology, National Research Council, Monterotondo, Rome, Italy; DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
| | - Rea Valaperta
- Molecular Biology Laboratory, Policlinico San Donato-IRCCS, San Donato Milanese, Milan, Italy
| | - Rosanna Cardani
- Muscle Histopathology and Molecular Biology Laboratory, Policlinico San Donato-IRCCS, San Donato Milanese, Milan, Italy
| | - Giovanni Meola
- Department of Neurology, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy; Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Fabio Martelli
- Molecular Cardiology Laboratory, Policlinico San Donato-IRCCS, San Donato Milanese, Milan, Italy
| | - Beatrice Cardinali
- Institute of Cell Biology and Neurobiology, National Research Council, Monterotondo, Rome, Italy.
| | - Germana Falcone
- Institute of Cell Biology and Neurobiology, National Research Council, Monterotondo, Rome, Italy.
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Jauvin D, Chrétien J, Pandey SK, Martineau L, Revillod L, Bassez G, Lachon A, MacLeod AR, Gourdon G, Wheeler TM, Thornton CA, Bennett CF, Puymirat J. Targeting DMPK with Antisense Oligonucleotide Improves Muscle Strength in Myotonic Dystrophy Type 1 Mice. MOLECULAR THERAPY. NUCLEIC ACIDS 2017. [PMID: 28624222 PMCID: PMC5453865 DOI: 10.1016/j.omtn.2017.05.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Myotonic dystrophy type 1 (DM1), a dominant hereditary muscular dystrophy, is caused by an abnormal expansion of a (CTG)n trinucleotide repeat in the 3′ UTR of the human dystrophia myotonica protein kinase (DMPK) gene. As a consequence, mutant transcripts containing expanded CUG repeats are retained in nuclear foci and alter the function of splicing regulatory factors members of the MBNL and CELF families, resulting in alternative splicing misregulation of specific transcripts in affected DM1 tissues. In the present study, we treated DMSXL mice systemically with a 2′-4′-constrained, ethyl-modified (ISIS 486178) antisense oligonucleotide (ASO) targeted to the 3′ UTR of the DMPK gene, which led to a 70% reduction in CUGexp RNA abundance and foci in different skeletal muscles and a 30% reduction in the heart. Furthermore, treatment with ISIS 486178 ASO improved body weight, muscle strength, and muscle histology, whereas no overt toxicity was detected. This is evidence that the reduction of CUGexp RNA improves muscle strength in DM1, suggesting that muscle weakness in DM1 patients may be improved following elimination of toxic RNAs.
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Affiliation(s)
- Dominic Jauvin
- Laval University Experimental Organogenesis Center/LOEX, Enfant-Jésus Hospital, Québec, QC G1J 1Z4, Canada
| | - Jessina Chrétien
- Laval University Experimental Organogenesis Center/LOEX, Enfant-Jésus Hospital, Québec, QC G1J 1Z4, Canada
| | - Sanjay K Pandey
- Ionis Pharmaceuticals, Inc., Carlsbad, CA 92010, USA; Triangulum Biopharma, San Diego, CA 92121, USA
| | - Laurie Martineau
- Laval University Experimental Organogenesis Center/LOEX, Enfant-Jésus Hospital, Québec, QC G1J 1Z4, Canada
| | - Lucille Revillod
- INSERM U955, Neuromuscular Reference Center, Henri-Mondor Hospital, Créteil 94000, France
| | - Guillaume Bassez
- INSERM U955, Neuromuscular Reference Center, Henri-Mondor Hospital, Créteil 94000, France
| | - Aline Lachon
- INSERM U781, Imagine Institute, Paris 75015, France
| | | | | | | | | | | | - Jack Puymirat
- Laval University Experimental Organogenesis Center/LOEX, Enfant-Jésus Hospital, Québec, QC G1J 1Z4, Canada; Department of Neurological Sciences CHU de Québec-Laval University, Enfant-Jésus Hospital, Québec, QC G1J 1Z4, Canada.
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25
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Gudde AEEG, van Kessel IDG, André LM, Wieringa B, Wansink DG. Trinucleotide-repeat expanded and normal DMPK transcripts contain unusually long poly(A) tails despite differential nuclear residence. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2017; 1860:740-749. [PMID: 28435090 DOI: 10.1016/j.bbagrm.2017.04.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 03/26/2017] [Accepted: 04/14/2017] [Indexed: 12/29/2022]
Abstract
In yeast and higher eukaryotes nuclear retention of transcripts may serve in control over RNA decay, nucleocytoplasmic transport and premature cytoplasmic appearance of mRNAs. Hyperadenylation of RNA is known to be associated with nuclear retention, but the cause-consequence relationship between hyperadenylation and regulation of RNA nuclear export is still unclear. We compared polyadenylation status between normal and expanded DMPK transcripts in muscle cells and tissues derived from unaffected individuals and patients with myotonic dystrophy type 1 (DM1). DM1 is an autosomal dominant disorder caused by (CTG)n repeat expansion in the DMPK gene. DM1 etiology is characterized by an almost complete block of nuclear export of DMPK transcripts carrying a long (CUG)n repeat, including aberrant sequestration of RNA-binding proteins. We show here by use of cell fractionation, RNA size separation and analysis of poly(A) tail length that a considerable fraction of transcripts from the normal DMPK allele is also retained in the nucleus (~30%). They carry poly(A) tails with an unusually broad length distribution, ranging between a few dozen to >500 adenosine residues. Remarkably, expanded DMPK (CUG)n transcripts from the mutant allele, almost exclusively nuclear, carry equally long poly(A) tails. Our findings thus suggest that nuclear retention may be a common feature of regulation of DMPK RNA expression. The typical forced nuclear residence of expanded DMPK transcripts affects this regulation in tissues of DM1 patients, but not through hyperadenylation.
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Affiliation(s)
- Anke E E G Gudde
- Radboud University Medical Centre, Radboud Institute for Molecular Life Sciences, Department of Cell Biology, Nijmegen, The Netherlands
| | - Ingeborg D G van Kessel
- Radboud University Medical Centre, Radboud Institute for Molecular Life Sciences, Department of Cell Biology, Nijmegen, The Netherlands
| | - Laurène M André
- Radboud University Medical Centre, Radboud Institute for Molecular Life Sciences, Department of Cell Biology, Nijmegen, The Netherlands
| | - Bé Wieringa
- Radboud University Medical Centre, Radboud Institute for Molecular Life Sciences, Department of Cell Biology, Nijmegen, The Netherlands
| | - Derick G Wansink
- Radboud University Medical Centre, Radboud Institute for Molecular Life Sciences, Department of Cell Biology, Nijmegen, The Netherlands.
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26
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Urbanek MO, Michalak M, Krzyzosiak WJ. 2D and 3D FISH of expanded repeat RNAs in human lymphoblasts. Methods 2017; 120:49-57. [PMID: 28404480 DOI: 10.1016/j.ymeth.2017.04.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 02/09/2017] [Accepted: 04/05/2017] [Indexed: 12/18/2022] Open
Abstract
The first methods for visualizing RNAs within cells were designed for simple imaging of specific transcripts in cells or tissues and since then significant technical advances have been made in this field. Today, high-resolution images can be obtained, enabling visualization of single transcript molecules, quantitative analyses of images, and precise localization of RNAs within cells as well as co-localization of transcripts with specific proteins or other molecules. In addition, tracking of RNA dynamics within single cell has become possible. RNA imaging techniques have been utilized for investigating the role of mutant RNAs in a number of human disorders caused by simple microsatellite expansions. These diseases include myotonic dystrophy type 1 and 2, amyotrophic lateral sclerosis/frontotemporal dementia, fragile X-associated tremor/ataxia syndrome, and Huntington's disease. Mutant RNAs with expanded repeats tend to aggregate predominantly within cell nuclei, forming structures called RNA foci. In this study, we demonstrate methods for fluorescent visualization of RNAs in both fixed and living cells using the example of RNAs containing various expanded repeat tracts (CUG, CCUG, GGGGCC, CGG, and CAG) from experiment design to image analysis. We describe in detail 2D and 3D fluorescence in situ hybridization (FISH) protocols for imaging expanded repeats RNAs, and we review briefly live imaging techniques used to characterize RNA foci formed by mutant RNAs. These methods could be used to image the entire cellular pathway of RNAs, from transcription to degradation.
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Affiliation(s)
- Martyna O Urbanek
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14 Str., 61-704 Poznan, Poland
| | - Michal Michalak
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14 Str., 61-704 Poznan, Poland
| | - Wlodzimierz J Krzyzosiak
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14 Str., 61-704 Poznan, Poland.
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27
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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: 65] [Impact Index Per Article: 9.3] [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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28
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Arandel L, Polay Espinoza M, Matloka M, Bazinet A, De Dea Diniz D, Naouar N, Rau F, Jollet A, Edom-Vovard F, Mamchaoui K, Tarnopolsky M, Puymirat J, Battail C, Boland A, Deleuze JF, Mouly V, Klein AF, Furling D. Immortalized human myotonic dystrophy muscle cell lines to assess therapeutic compounds. Dis Model Mech 2017; 10:487-497. [PMID: 28188264 PMCID: PMC5399563 DOI: 10.1242/dmm.027367] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 02/05/2017] [Indexed: 01/20/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) and type 2 (DM2) are autosomal dominant neuromuscular diseases caused by microsatellite expansions and belong to the family of RNA-dominant disorders. Availability of cellular models in which the DM mutation is expressed within its natural context is essential to facilitate efforts to identify new therapeutic compounds. Here, we generated immortalized DM1 and DM2 human muscle cell lines that display nuclear RNA aggregates of expanded repeats, a hallmark of myotonic dystrophy. Selected clones of DM1 and DM2 immortalized myoblasts behave as parental primary myoblasts with a reduced fusion capacity of immortalized DM1 myoblasts when compared with control and DM2 cells. Alternative splicing defects were observed in differentiated DM1 muscle cell lines, but not in DM2 lines. Splicing alterations did not result from differentiation delay because similar changes were found in immortalized DM1 transdifferentiated fibroblasts in which myogenic differentiation has been forced by overexpression of MYOD1. As a proof-of-concept, we show that antisense approaches alleviate disease-associated defects, and an RNA-seq analysis confirmed that the vast majority of mis-spliced events in immortalized DM1 muscle cells were affected by antisense treatment, with half of them significantly rescued in treated DM1 cells. Immortalized DM1 muscle cell lines displaying characteristic disease-associated molecular features such as nuclear RNA aggregates and splicing defects can be used as robust readouts for the screening of therapeutic compounds. Therefore, immortalized DM1 and DM2 muscle cell lines represent new models and tools to investigate molecular pathophysiological mechanisms and evaluate the in vitro effects of compounds on RNA toxicity associated with myotonic dystrophy mutations. Summary: Myotonic dystrophy muscle cell models displaying characteristic disease-associated molecular features can be used to investigate molecular pathophysiological mechanisms and evaluate therapeutic approaches.
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Affiliation(s)
- Ludovic Arandel
- Sorbonne Universités UPMC Univ Paris 06, INSERM, CNRS, Centre de Recherche en Myologie, Institut de Myologie, GH Pitié-Salpêtrière, Paris 75013, France
| | - Micaela Polay Espinoza
- Sorbonne Universités UPMC Univ Paris 06, INSERM, CNRS, Centre de Recherche en Myologie, Institut de Myologie, GH Pitié-Salpêtrière, Paris 75013, France
| | - Magdalena Matloka
- Sorbonne Universités UPMC Univ Paris 06, INSERM, CNRS, Centre de Recherche en Myologie, Institut de Myologie, GH Pitié-Salpêtrière, Paris 75013, France
| | - Audrey Bazinet
- Sorbonne Universités UPMC Univ Paris 06, INSERM, CNRS, Centre de Recherche en Myologie, Institut de Myologie, GH Pitié-Salpêtrière, Paris 75013, France
| | - Damily De Dea Diniz
- Sorbonne Universités UPMC Univ Paris 06, INSERM, CNRS, Centre de Recherche en Myologie, Institut de Myologie, GH Pitié-Salpêtrière, Paris 75013, France
| | - Naïra Naouar
- Sorbonne Universités UPMC Univ Paris 06, INSERM, CNRS, Centre de Recherche en Myologie, Institut de Myologie, GH Pitié-Salpêtrière, Paris 75013, France
| | - Frédérique Rau
- Sorbonne Universités UPMC Univ Paris 06, INSERM, CNRS, Centre de Recherche en Myologie, Institut de Myologie, GH Pitié-Salpêtrière, Paris 75013, France
| | - Arnaud Jollet
- Sorbonne Universités UPMC Univ Paris 06, INSERM, CNRS, Centre de Recherche en Myologie, Institut de Myologie, GH Pitié-Salpêtrière, Paris 75013, France
| | - Frédérique Edom-Vovard
- Sorbonne Universités UPMC Univ Paris 06, INSERM, CNRS, Centre de Recherche en Myologie, Institut de Myologie, GH Pitié-Salpêtrière, Paris 75013, France
| | - Kamel Mamchaoui
- Sorbonne Universités UPMC Univ Paris 06, INSERM, CNRS, Centre de Recherche en Myologie, Institut de Myologie, GH Pitié-Salpêtrière, Paris 75013, France
| | - Mark Tarnopolsky
- McMaster University Medical Center, Departments of Pediatrics and Medicine, 1200 Main St W., Hamilton, Ontario, Canada, L8N 3Z5
| | - Jack Puymirat
- CHU de Quebec, site Enfant-Jésus, Université Laval, Québec, Canada G1J 1Z4
| | - Christophe Battail
- Centre National de Génotypage, Institut de Génomique, CEA, 91000 Evry, France
| | - Anne Boland
- Centre National de Génotypage, Institut de Génomique, CEA, 91000 Evry, France
| | | | - Vincent Mouly
- Sorbonne Universités UPMC Univ Paris 06, INSERM, CNRS, Centre de Recherche en Myologie, Institut de Myologie, GH Pitié-Salpêtrière, Paris 75013, France
| | - Arnaud F Klein
- Sorbonne Universités UPMC Univ Paris 06, INSERM, CNRS, Centre de Recherche en Myologie, Institut de Myologie, GH Pitié-Salpêtrière, Paris 75013, France
| | - Denis Furling
- Sorbonne Universités UPMC Univ Paris 06, INSERM, CNRS, Centre de Recherche en Myologie, Institut de Myologie, GH Pitié-Salpêtrière, Paris 75013, France
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29
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Precise small-molecule recognition of a toxic CUG RNA repeat expansion. Nat Chem Biol 2016; 13:188-193. [PMID: 27941760 DOI: 10.1038/nchembio.2251] [Citation(s) in RCA: 132] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 10/03/2016] [Indexed: 01/10/2023]
Abstract
Excluding the ribosome and riboswitches, developing small molecules that selectively target RNA is a longstanding problem in chemical biology. A typical cellular RNA is difficult to target because it has little tertiary, but abundant secondary structure. We designed allele-selective compounds that target such an RNA, the toxic noncoding repeat expansion (r(CUG)exp) that causes myotonic dystrophy type 1 (DM1). We developed several strategies to generate allele-selective small molecules, including non-covalent binding, covalent binding, cleavage and on-site probe synthesis. Covalent binding and cleavage enabled target profiling in cells derived from individuals with DM1, showing precise recognition of r(CUG)exp. In the on-site probe synthesis approach, small molecules bound adjacent sites in r(CUG)exp and reacted to afford picomolar inhibitors via a proximity-based click reaction only in DM1-affected cells. We expanded this approach to image r(CUG)exp in its natural context.
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30
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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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31
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Urbanek MO, Jazurek M, Switonski PM, Figura G, Krzyzosiak WJ. Nuclear speckles are detention centers for transcripts containing expanded CAG repeats. Biochim Biophys Acta Mol Basis Dis 2016; 1862:1513-20. [PMID: 27239700 DOI: 10.1016/j.bbadis.2016.05.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 05/18/2016] [Accepted: 05/26/2016] [Indexed: 12/13/2022]
Abstract
The human genetic disorders caused by CAG repeat expansions in the translated sequences of various genes are called polyglutamine (polyQ) diseases because of the cellular "toxicity" of the mutant proteins. The contribution of mutant transcripts to the pathogenesis of these diseases is supported by several observations obtained from cellular models of these disorders. Here, we show that the common feature of cell lines modeling polyQ diseases is the formation of nuclear CAG RNA foci. We performed qualitative and quantitative analyses of these foci in numerous cellular models endogenously and exogenously expressing mutant transcripts by fluorescence in situ hybridization (FISH). We compared the CAG RNA foci of polyQ diseases with the CUG foci of myotonic dystrophy type 1 and found substantial differences in their number and morphology. Smaller differences within the polyQ disease group were also revealed and included a positive correlation between the foci number and the CAG repeat length. We show that expanded CAA repeats, also encoding glutamine, did not trigger RNA foci formation and foci formation is independent of the presence of mutant polyglutamine protein. Using FISH combined with immunofluorescence, we demonstrated partial co-localization of CAG repeat foci with MBNL1 alternative splicing factor, which explains the mild deregulation of MBNL1-dependent genes. We also showed that foci reside within nuclear speckles in diverse cell types: fibroblasts, lymphoblasts, iPS cells and neuronal progenitors and remain dependent on integrity of these nuclear structures.
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Affiliation(s)
- Martyna O Urbanek
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14 Str., 61-704 Poznan, Poland
| | - Magdalena Jazurek
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14 Str., 61-704 Poznan, Poland
| | - Pawel M Switonski
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14 Str., 61-704 Poznan, Poland
| | - Grzegorz Figura
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14 Str., 61-704 Poznan, Poland
| | - Wlodzimierz J Krzyzosiak
- Department of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14 Str., 61-704 Poznan, Poland.
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32
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Actinomycin D Specifically Reduces Expanded CUG Repeat RNA in Myotonic Dystrophy Models. Cell Rep 2015; 13:2386-2394. [PMID: 26686629 DOI: 10.1016/j.celrep.2015.11.028] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 09/10/2015] [Accepted: 11/06/2015] [Indexed: 01/16/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) is an inherited disease characterized by the inability to relax contracted muscles. Affected individuals carry large CTG expansions that are toxic when transcribed. One possible treatment approach is to reduce or eliminate transcription of CTG repeats. Actinomycin D (ActD) is a potent transcription inhibitor and FDA-approved chemotherapeutic that binds GC-rich DNA with high affinity. Here, we report that ActD decreased CUG transcript levels in a dose-dependent manner in DM1 cell and mouse models at significantly lower concentrations (nanomolar) compared to its use as a general transcription inhibitor or chemotherapeutic. ActD also significantly reversed DM1-associated splicing defects in a DM1 mouse model, and did so within the currently approved human treatment range. RNA-seq analyses showed that low concentrations of ActD did not globally inhibit transcription in a DM1 mouse model. These results indicate that transcription inhibition of CTG expansions is a promising treatment approach for DM1.
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Abstract
For many decades, the major function of mRNA was thought to be to provide protein-coding information embedded in the genome. The advent of high-throughput sequencing has led to the discovery of pervasive transcription of eukaryotic genomes and opened the world of RNA-mediated gene regulation. Many regulatory RNAs have been found to be incapable of protein coding and are hence termed as non-coding RNAs (ncRNAs). However, studies in recent years have shown that several previously annotated non-coding RNAs have the potential to encode proteins, and conversely, some coding RNAs have regulatory functions independent of the protein they encode. Such bi-functional RNAs, with both protein coding and non-coding functions, which we term as 'cncRNAs', have emerged as new players in cellular systems. Here, we describe the functions of some cncRNAs identified from bacteria to humans. Because the functions of many RNAs across genomes remains unclear, we propose that RNAs be classified as coding, non-coding or both only after careful analysis of their functions.
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Affiliation(s)
- Pooja Kumari
- Division of Biomedical Cell Biology, Warwick Medical School, The University of Warwick, Gibbet Hill Road, Coventry CV47AJ, United Kingdom
| | - Karuna Sampath
- Division of Biomedical Cell Biology, Warwick Medical School, The University of Warwick, Gibbet Hill Road, Coventry CV47AJ, United Kingdom.
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34
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Laustriat D, Gide J, Barrault L, Chautard E, Benoit C, Auboeuf D, Boland A, Battail C, Artiguenave F, Deleuze JF, Bénit P, Rustin P, Franc S, Charpentier G, Furling D, Bassez G, Nissan X, Martinat C, Peschanski M, Baghdoyan S. In Vitro and In Vivo Modulation of Alternative Splicing by the Biguanide Metformin. MOLECULAR THERAPY-NUCLEIC ACIDS 2015; 4:e262. [PMID: 26528939 PMCID: PMC4877444 DOI: 10.1038/mtna.2015.35] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 09/22/2015] [Indexed: 01/02/2023]
Abstract
Major physiological changes are governed by alternative splicing of RNA, and its misregulation may lead to specific diseases. With the use of a genome-wide approach, we show here that this splicing step can be modified by medication and demonstrate the effects of the biguanide metformin, on alternative splicing. The mechanism of action involves AMPK activation and downregulation of the RBM3 RNA-binding protein. The effects of metformin treatment were tested on myotonic dystrophy type I (DM1), a multisystemic disease considered to be a spliceopathy. We show that this drug promotes a corrective effect on several splicing defects associated with DM1 in derivatives of human embryonic stem cells carrying the causal mutation of DM1 as well as in primary myoblasts derived from patients. The biological effects of metformin were shown to be compatible with typical therapeutic dosages in a clinical investigation involving diabetic patients. The drug appears to act as a modifier of alternative splicing of a subset of genes and may therefore have novel therapeutic potential for many more diseases besides those directly linked to defective alternative splicing.
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Affiliation(s)
| | | | | | - Emilie Chautard
- Centre de Recherche en Cancérologie de Lyon, INSERM U1052, Centre Léon Bérard, Lyon, France.,Université Lyon 1, CNRS, UMR 5558, INRIA Bamboo, Villeurbanne, France
| | - Clara Benoit
- Centre de Recherche en Cancérologie de Lyon, INSERM U1052, Centre Léon Bérard, Lyon, France
| | - Didier Auboeuf
- Centre de Recherche en Cancérologie de Lyon, INSERM U1052, Centre Léon Bérard, Lyon, France
| | - Anne Boland
- Centre National de Génotypage, Institut de Génomique, CEA, Evry, France
| | | | | | | | - Paule Bénit
- INSERM UMR 1141, Hôpital Robert Debré, Paris, France.,Université Paris 7, Faculté de Médecine Denis Diderot, Paris, France
| | - Pierre Rustin
- INSERM UMR 1141, Hôpital Robert Debré, Paris, France.,Université Paris 7, Faculté de Médecine Denis Diderot, Paris, France
| | - Sylvia Franc
- Centre Hospitalier Sud Francilien and CERITD, Evry Cedex, France
| | | | - Denis Furling
- Sorbonne Universités, UPMC Université Paris 06, Centre de Recherche en Myologie, INSERM UMRS974, CNRS FRE3617, Institut de Myologie, Paris 75013, France
| | - Guillaume Bassez
- GH Henri Mondor, Inserm U955, Université Paris Est, Créteil, France
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35
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Delaleau M, Borden KLB. Multiple Export Mechanisms for mRNAs. Cells 2015; 4:452-73. [PMID: 26343730 PMCID: PMC4588045 DOI: 10.3390/cells4030452] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 08/20/2015] [Accepted: 08/21/2015] [Indexed: 12/20/2022] Open
Abstract
Nuclear mRNA export plays an important role in gene expression. We describe the mechanisms of mRNA export including the importance of mRNP assembly, docking with the nuclear basket of the nuclear pore complex (NPC), transit through the central channel of the NPC and cytoplasmic release. We describe multiple mechanisms of mRNA export including NXF1 and CRM1 mediated pathways. Selective groups of mRNAs can be preferentially transported in order to respond to cellular stimuli. RNAs can be selected based on the presence of specific cis-acting RNA elements and binding of specific adaptor proteins. The role that dysregulation of this process plays in human disease is also discussed.
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Affiliation(s)
- Mildred Delaleau
- Department of Pathology and Cell Biology, Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, H3C 3J7, Canada.
| | - Katherine L B Borden
- Department of Pathology and Cell Biology, Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, H3C 3J7, Canada.
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36
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Siboni RB, Bodner MJ, Khalifa MM, Docter AG, Choi JY, Nakamori M, Haley MM, Berglund JA. Biological Efficacy and Toxicity of Diamidines in Myotonic Dystrophy Type 1 Models. J Med Chem 2015; 58:5770-80. [PMID: 26103061 PMCID: PMC4972181 DOI: 10.1021/acs.jmedchem.5b00356] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Myotonic dystrophy type 1 (DM1) is a disease characterized by errors in alternative splicing, or "mis-splicing". The causative agent of mis-splicing in DM1 is an inherited CTG repeat expansion located in the 3' untranslated region of the DM protein kinase gene. When transcribed, CUG repeat expansion RNA sequesters muscleblind-like (MBNL) proteins, which constitute an important family of alternative splicing regulators. Sequestration of MBNL proteins results in the mis-splicing of its regulated transcripts. Previous work has demonstrated that pentamidine, a diamidine which is currently FDA-approved as an antiparasitic agent, was able to partially reverse mis-splicing in multiple DM1 models, albeit at toxic concentrations. In this study, we characterized a series of pentamidine analogues to determine their ability to reverse mis-splicing and their toxicity in vivo. Experiments in cell and mouse models demonstrated that compound 13, also known as furamidine, effectively reversed mis-splicing with equal efficacy and reduced toxicity compared to pentamidine.
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Affiliation(s)
| | | | | | | | | | - Masayuki Nakamori
- §Department of Neurology, University of Osaka Graduate School of Medicine, Osaka 565-0871, Japan
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37
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Pettersson OJ, Aagaard L, Jensen TG, Damgaard CK. Molecular mechanisms in DM1 - a focus on foci. Nucleic Acids Res 2015; 43:2433-41. [PMID: 25605794 PMCID: PMC4344492 DOI: 10.1093/nar/gkv029] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 01/05/2015] [Accepted: 01/11/2015] [Indexed: 01/15/2023] Open
Abstract
Myotonic dystrophy type 1 is caused by abnormal expansion of a CTG-trinucleotide repeat in the gene encoding Dystrophia Myotonica Protein Kinase (DMPK), which in turn leads to global deregulation of gene expression in affected individuals. The transcribed mRNA contains a massive CUG-expansion in the 3' untranslated region (3'UTR) facilitating nucleation of several regulatory RNA-binding proteins, which are thus unable to perform their normal cellular function. These CUG-expanded mRNA-protein aggregates form distinct, primarily nuclear foci. In differentiated muscle cells, most of the CUG-expanded RNA remains in the nuclear compartment, while in dividing cells such as fibroblasts a considerable fraction of the mutant RNA reaches the cytoplasm, consistent with findings that both nuclear and cytoplasmic events are mis-regulated in DM1. Recent evidence suggests that the nuclear aggregates, or ribonuclear foci, are more dynamic than previously anticipated and regulated by several proteins, including RNA helicases. In this review, we focus on the homeostasis of DMPK mRNA foci and discuss how their dynamic regulation may affect disease-causing mechanisms in DM1.
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Affiliation(s)
- Olof Joakim Pettersson
- Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 4, Building 1240, DK-8000 Aarhus C, Denmark
| | - Lars Aagaard
- Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 4, Building 1240, DK-8000 Aarhus C, Denmark
| | - Thomas Gryesten Jensen
- Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 4, Building 1240, DK-8000 Aarhus C, Denmark
| | - Christian Kroun Damgaard
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, Building 1130, DK-8000 Aarhus C, Denmark
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38
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Pettersson OJ, Aagaard L, Andrejeva D, Thomsen R, Jensen TG, Damgaard CK. DDX6 regulates sequestered nuclear CUG-expanded DMPK-mRNA in dystrophia myotonica type 1. Nucleic Acids Res 2014; 42:7186-200. [PMID: 24792155 PMCID: PMC4066779 DOI: 10.1093/nar/gku352] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) is caused by CUG triplet expansions in the 3′ UTR of dystrophia myotonica protein kinase (DMPK) messenger ribonucleic acid (mRNA). The etiology of this multi-systemic disease involves pre-mRNA splicing defects elicited by the ability of the CUG-expanded mRNA to ‘sponge’ splicing factors of the muscleblind family. Although nuclear aggregation of CUG-containing mRNPs in distinct foci is a hallmark of DM1, the mechanisms of their homeostasis have not been completely elucidated. Here we show that a DEAD-box helicase, DDX6, interacts with CUG triplet-repeat mRNA in primary fibroblasts from DM1 patients and with CUG–RNA in vitro. DDX6 overexpression relieves DM1 mis-splicing, and causes a significant reduction in nuclear DMPK-mRNA foci. Conversely, knockdown of endogenous DDX6 leads to a significant increase in DMPK-mRNA foci count and to increased sequestration of MBNL1 in the nucleus. While the level of CUG-expanded mRNA is unaffected by increased DDX6 expression, the mRNA re-localizes to the cytoplasm and its interaction partner MBNL1 becomes dispersed and also partially re-localized to the cytoplasm. Finally, we show that DDX6 unwinds CUG-repeat duplexes in vitro in an adenosinetriphosphate-dependent manner, suggesting that DDX6 can remodel and release nuclear DMPK messenger ribonucleoprotein foci, leading to normalization of pathogenic alternative splicing events.
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Affiliation(s)
- Olof J Pettersson
- Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 4, Building 1240, DK-8000 Aarhus C, Denmark
| | - Lars Aagaard
- Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 4, Building 1240, DK-8000 Aarhus C, Denmark
| | - Diana Andrejeva
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, building 1131, DK-8000 Aarhus C, Denmark
| | - Rune Thomsen
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, building 1131, DK-8000 Aarhus C, Denmark
| | - Thomas G Jensen
- Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 4, Building 1240, DK-8000 Aarhus C, Denmark
| | - Christian K Damgaard
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, building 1131, DK-8000 Aarhus C, Denmark
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39
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MBNL1 and RBFOX2 cooperate to establish a splicing programme involved in pluripotent stem cell differentiation. Nat Commun 2014; 4:2480. [PMID: 24048253 DOI: 10.1038/ncomms3480] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 08/21/2013] [Indexed: 02/08/2023] Open
Abstract
Reprogramming somatic cells into induced pluripotent stem cells (iPSCs) has provided huge insight into the pathways, mechanisms and transcription factors that control differentiation. Here we use high-throughput RT-PCR technology to take a snapshot of splicing changes in the full spectrum of high- and low-expressed genes during induction of fibroblasts, from several donors, into iPSCs and their subsequent redifferentiation. We uncover a programme of concerted alternative splicing changes involved in late mesoderm differentiation and controlled by key splicing regulators MBNL1 and RBFOX2. These critical splicing adjustments arise early in vertebrate evolution and remain fixed in at least 10 genes (including PLOD2, CLSTN1, ATP2A1, PALM, ITGA6, KIF13A, FMNL3, PPIP5K1, MARK2 and FNIP1), implying that vertebrates require alternative splicing to fully implement the instructions of transcriptional control networks.
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40
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Transcriptionally correlated subcellular dynamics of MBNL1 during lens development and their implication for the molecular pathology of myotonic dystrophy type 1. Biochem J 2014; 458:267-80. [PMID: 24354850 DOI: 10.1042/bj20130870] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
DM1 (myotonic dystrophy type 1) is caused by elongation of a CTG repeat in the DMPK (dystrophia myotonica-protein kinase) gene. mRNA transcripts containing these CUGexp (CUG expansion) repeats form accumulations, or foci, in the nucleus of the cell. The pathogenesis of DM1 is proposed to result from inappropriate patterns of alternative splicing caused by sequestration of the developmentally regulated alternative splicing factor MBNL1 (muscleblind-like 1) by these foci. Since eye lens cataract is a common feature of DM1 we have examined the distribution and dynamics of MBNL1 in lens epithelial cell lines derived from patients with DM1. The results of the present study demonstrate that only a small proportion of nuclear MBNL1 accumulates in CUGexp pre-mRNA foci. MBNL1 is, however, highly mobile and changes localization in response to altered transcription and splicing activity. Moreover, immunolocalization studies in lens sections suggest that a change in MBNL1 distribution is important during lens growth and differentiation. Although these data suggest that the loss of MBNL1 function due to accumulation in foci is an unlikely explanation for DM1 symptoms in the lens, they do demonstrate a strong relationship between the subcellular MBNL1 localization and pathways of cellular differentiation, providing an insight into the sensitivity of the lens to changes in MBNL1 distribution.
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41
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Induction and reversal of myotonic dystrophy type 1 pre-mRNA splicing defects by small molecules. Nat Commun 2013; 4:2044. [PMID: 23806903 PMCID: PMC3710115 DOI: 10.1038/ncomms3044] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 05/23/2013] [Indexed: 02/06/2023] Open
Abstract
The ability to control pre-mRNA splicing with small molecules could facilitate the development of therapeutics or cell-based circuits that control gene function. Myotonic dystrophy type 1 (DM1) is caused by the dysregulation of alternative pre-mRNA splicing due to sequestration of muscleblind-like 1 protein (MBNL1) by expanded, non-coding r(CUG) repeats (r(CUG)exp). Here we report two small molecules that induce or ameliorate alternative splicing dysregulation. The thiophene-containing small molecule (1) inhibits the interaction of MBNL1 with its natural pre-mRNA substrates. Compound (2), a substituted naphthyridine, binds r(CUG)exp and displaces MBNL1. Structural models show that 1 binds MBNL1 in the Zn-finger domain and that 2 interacts with UU loops in r(CUG)exp. This study provides a structural framework for small molecules that target MBNL1 by mimicking r(CUG)exp and shows that targeting MBNL1 causes dysregulation of alternative splicing, suggesting that MBNL1 is thus not a suitable therapeutic target for the treatment of DM1.
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42
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Ketley A, Chen CZ, Li X, Arya S, Robinson TE, Granados-Riveron J, Udosen I, Morris GE, Holt I, Furling D, Chaouch S, Haworth B, Southall N, Shinn P, Zheng W, Austin CP, Hayes CJ, Brook JD. High-content screening identifies small molecules that remove nuclear foci, affect MBNL distribution and CELF1 protein levels via a PKC-independent pathway in myotonic dystrophy cell lines. Hum Mol Genet 2013; 23:1551-62. [PMID: 24179176 PMCID: PMC3929092 DOI: 10.1093/hmg/ddt542] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Myotonic dystrophy (DM) is a multi-system neuromuscular disorder for which there is no treatment. We have developed a medium throughput phenotypic assay, based on the identification of nuclear foci in DM patient cell lines using in situ hybridization and high-content imaging to screen for potentially useful therapeutic compounds. A series of further assays based on molecular features of DM have also been employed. Two compounds that reduce and/or remove nuclear foci have been identified, Ro 31-8220 and chromomycin A3. Ro 31-8220 is a PKC inhibitor, previously shown to affect the hyperphosphorylation of CELF1 and ameliorate the cardiac phenotype in a DM1 mouse model. We show that the same compound eliminates nuclear foci, reduces MBNL1 protein in the nucleus, affects ATP2A1 alternative splicing and reduces steady-state levels of CELF1 protein. We demonstrate that this effect is independent of PKC activity and conclude that this compound may be acting on alternative kinase targets within DM pathophysiology. Understanding the activity profile for this compound is key for the development of targeted therapeutics in the treatment of DM.
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Affiliation(s)
- Ami Ketley
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK
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43
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Guan L, Disney MD. Covalent Small-Molecule-RNA Complex Formation Enables Cellular Profiling of Small-Molecule-RNA Interactions. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201301639] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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44
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Guan L, Disney MD. Covalent small-molecule-RNA complex formation enables cellular profiling of small-molecule-RNA interactions. Angew Chem Int Ed Engl 2013; 52:10010-3. [PMID: 23913698 DOI: 10.1002/anie.201301639] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 05/02/2013] [Indexed: 01/13/2023]
Abstract
Won't let you go! A strategy is described to design small molecules that react with their cellular RNA targets. This approach not only improves the activity of compounds targeting RNA in cell culture by a factor of about 2500 but also enables cell-wide profiling of its RNA targets.
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Affiliation(s)
- Lirui Guan
- Department of Chemistry, The Scripps Research Institute, Scripps Florida, 130 Scripps Way, 3A1, Jupiter, FL 33458 (USA)
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45
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Abstract
The passage of mRNA molecules from the site of synthesis, through the nucleoplasm and the nuclear pore, en route to the cytoplasm, might appear straightforward. Nonetheless, several decades of detailed examination of this pathway, from high resolution electron microscopy in fixed specimens, through the development of immuno-detection techniques and fluorescence toolkits, to the current era of live-cell imaging, show this to be an eventful journey. In addition to mRNAs, several species of noncoding RNAs travel and function in the nucleus, some being retained within throughout their lifetime. This review will highlight the nucleoplasmic paths taken by mRNAs and noncoding RNAs in eukaryotic cells with special focus on live-cell data and in concurrence with the biophysical nature of the nucleus.
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Affiliation(s)
- Jonathan Sheinberger
- The Mina & Everard Goodman Faculty of Life Sciences & Institute of Nanotechnology, Bar-Ilan University, Ramat Gan, Israel
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46
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Jog SP, Paul S, Dansithong W, Tring S, Comai L, Reddy S. RNA splicing is responsive to MBNL1 dose. PLoS One 2012; 7:e48825. [PMID: 23166594 PMCID: PMC3499511 DOI: 10.1371/journal.pone.0048825] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Accepted: 10/03/2012] [Indexed: 11/24/2022] Open
Abstract
Myotonic dystrophy (DM1) is a highly variable, multi-system disorder resulting from the expansion of an untranslated CTG tract in DMPK. In DM1 expanded CUG repeat RNAs form hairpin secondary structures that bind and aberrantly sequester the RNA splice regulator, MBNL1. RNA splice defects resulting as a consequence of MBNL1 depletion have been shown to play a key role in the development of DM1 pathology. In patient populations, both the number and severity of DM1 symptoms increase broadly as a function of CTG tract length. However significant variability in the DM1 phenotype is observed in patients encoding similar CTG repeat numbers. Here we demonstrate that a gradual decrease in MBNL1 levels results both in the expansion of the repertoire of splice defects and an increase in the severity of the splice alterations. Thus, MBNL1 loss does not have an all or none outcome but rather shows a graded effect on the number and severity of the ensuing splice defects. Our results suggest that once a critical threshold is reached, relatively small dose variations of free MBNL1 levels, which may reflect modest changes in the size of the CUG tract or the extent of hairpin secondary structure formation, can significantly alter the number and severity of splice abnormalities and thus contribute to the phenotype variability observed in DM1 patients.
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Affiliation(s)
- Sonali P Jog
- Department of Biochemistry and Molecular Biology, Institute for Genetic Medicine, University of Southern California, Los Angeles, California, USA
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47
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Lukáš Z, Falk M, Feit J, Souček O, Falková I, Štefančíková L, Janoušová E, Fajkusová L, Zaorálková J, Hrabálková R. Sequestration of MBNL1 in tissues of patients with myotonic dystrophy type 2. Neuromuscul Disord 2012; 22:604-16. [DOI: 10.1016/j.nmd.2012.03.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Revised: 03/02/2012] [Accepted: 03/06/2012] [Indexed: 12/20/2022]
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48
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Laurent FX, Sureau A, Klein AF, Trouslard F, Gasnier E, Furling D, Marie J. New function for the RNA helicase p68/DDX5 as a modifier of MBNL1 activity on expanded CUG repeats. Nucleic Acids Res 2011; 40:3159-71. [PMID: 22156369 PMCID: PMC3326330 DOI: 10.1093/nar/gkr1228] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Myotonic Dystrophy type I (DM1) is caused by an abnormal expansion of CTG triplets in the 3′ UTR of the dystrophia myotonica protein kinase (DMPK) gene, leading to the aggregation of the mutant transcript in nuclear RNA foci. The expanded mutant transcript promotes the sequestration of the MBNL1 splicing factor, resulting in the misregulation of a subset of alternative splicing events. In this study, we identify the DEAD-box RNA helicase p68 (DDX5) in complexes assembled onto in vitro-transcribed CUG repeats. We showed that p68 colocalized with RNA foci in cells expressing the 3′UTR of the DMPK gene containing expanded CTG repeats. We found that p68 increased MBNL1 binding onto pathological repeats and the stem–loop structure regulatory element within the cardiac Troponin T (TNNT2) pre-mRNA, splicing of which is misregulated in DM1. Mutations in the helicase core of p68 prevented both the stimulatory effect of the protein on MBNL1 binding and the colocalization of p68 with CUG repeats, suggesting that remodeling of RNA secondary structure by p68 facilitates MBNL1 binding. We also found that the competence of p68 for regulating TNNT2 exon 5 inclusion depended on the integrity of MBNL1 binding sites. We propose that p68 acts as a modifier of MBNL1 activity on splicing targets and pathogenic RNA.
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Affiliation(s)
- François-Xavier Laurent
- Centre de Génétique Moléculaire, CNRS, UPR 3404, Avenue de Terrasse, 91198 Gif-sur-Yvette, Université Paris-Sud, Orsay, France
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49
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Sewry CA, Quinlivan RCM, Squier W, Morris GE, Holt I. A rapid immunohistochemical test to distinguish congenital myotonic dystrophy from X-linked myotubular myopathy. Neuromuscul Disord 2011; 22:225-30. [PMID: 22113158 DOI: 10.1016/j.nmd.2011.10.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 09/05/2011] [Accepted: 10/05/2011] [Indexed: 12/11/2022]
Abstract
Severe forms of myotubular myopathy (MTM) and congenital myotonic dystrophy type 1 (CDM), both present as floppy infants with hypotonia, respiratory failure and bulbar insufficiency. Muscle biopsy is often performed as part of the diagnostic process, but these two disorders share very similar histopathological features. It is well documented that CDM muscle has nuclear foci that contain muscleblind-like 1 (MBNL1) protein. In muscle biopsies from eight neonates showing central nuclei, MBNL1 immunolocalisation identified discrete, intensely stained foci in three cases that were subsequently confirmed as CDM by DNA analysis. In the five remaining non-CDM patients and two controls, MBNL1 staining was heterogeneous in nuclei, not as foci. MBNL1 staining patterns in CDM were easily distinguishable from MTM. We suggest that in cases of hypotonia with suspected CDM or MTM, when biopsy has been taken, sections should additionally be stained for MBNL1 to provide a rapid indication of a CDM diagnosis.
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Affiliation(s)
- Caroline A Sewry
- Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital NHS Foundation Trust, Oswestry, Shropshire SY10 7AG, UK
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50
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Paul S, Dansithong W, Jog SP, Holt I, Mittal S, Brook JD, Morris GE, Comai L, Reddy S. Expanded CUG repeats Dysregulate RNA splicing by altering the stoichiometry of the muscleblind 1 complex. J Biol Chem 2011; 286:38427-38438. [PMID: 21900255 PMCID: PMC3207417 DOI: 10.1074/jbc.m111.255224] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Revised: 08/29/2011] [Indexed: 01/27/2023] Open
Abstract
To understand the role of the splice regulator muscleblind 1 (MBNL1) in the development of RNA splice defects in myotonic dystrophy I (DM1), we purified RNA-independent MBNL1 complexes from normal human myoblasts and examined the behavior of these complexes in DM1 myoblasts. Antibodies recognizing MBNL1 variants (MBNL1(CUG)), which can sequester in the toxic CUG RNA foci that develop in DM1 nuclei, were used to purify MBNL1(CUG) complexes from normal myoblasts. In normal myoblasts, MBNL1(CUG) bind 10 proteins involved in remodeling ribonucleoprotein complexes including hnRNP H, H2, H3, F, A2/B1, K, L, DDX5, DDX17, and DHX9. Of these proteins, only MBNL1(CUG) colocalizes extensively with DM1 CUG foci (>80% of foci) with its partners being present in <10% of foci. Importantly, the stoichiometry of MBNL1(CUG) complexes is altered in DM1 myoblasts, demonstrating an increase in the steady state levels of nine of its partner proteins. These changes are recapitulated by the expression of expanded CUG repeat RNA in Cos7 cells. Altered stoichiometry of MBNL1(CUG) complexes results from aberrant protein synthesis or stability and is unlinked to PKCα function. Modeling these changes in normal myoblasts demonstrates that increased levels of hnRNP H, H2, H3, F, and DDX5 independently dysregulate splicing in overlapping RNA subsets. Thus expression of expanded CUG repeats alters the stoichiometry of MBNL1(CUG) complexes to allow both the reinforcement and expansion of RNA processing defects.
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Affiliation(s)
- Sharan Paul
- Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, California 90033
| | - Warunee Dansithong
- Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, California 90033
| | - Sonali P Jog
- Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, California 90033
| | - Ian Holt
- Wolfson Centre for Inherited Neuromuscular Disease, Robert Jones and Agnes Hunt Orthopedic Hospital, Oswestry SY10 7AG, United Kingdom; Institute for Science and Technology in Medicine, Keele University, Keele ST5 5BG, United Kingdom
| | - Saloni Mittal
- Institute of Genetics, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, United Kingdom
| | - J David Brook
- Institute of Genetics, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, United Kingdom
| | - Glenn E Morris
- Wolfson Centre for Inherited Neuromuscular Disease, Robert Jones and Agnes Hunt Orthopedic Hospital, Oswestry SY10 7AG, United Kingdom; Institute for Science and Technology in Medicine, Keele University, Keele ST5 5BG, United Kingdom
| | - Lucio Comai
- Department Molecular Microbiology and Immunology, Institute for Genetic Medicine, University of Southern California, Los Angeles, California 90033.
| | - Sita Reddy
- Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, California 90033.
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