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Baud A, Derbis M, Tutak K, Sobczak K. Partners in crime: Proteins implicated in
RNA
repeat expansion diseases. WIRES RNA 2022; 13:e1709. [PMID: 35229468 PMCID: PMC9539487 DOI: 10.1002/wrna.1709] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 12/07/2021] [Accepted: 12/08/2021] [Indexed: 11/06/2022]
Affiliation(s)
- Anna Baud
- Department of Gene Expression Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University Poznan Poland
| | - Magdalena Derbis
- Department of Gene Expression Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University Poznan Poland
| | - Katarzyna Tutak
- Department of Gene Expression Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University Poznan Poland
| | - Krzysztof Sobczak
- Department of Gene Expression Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University Poznan Poland
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2
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Casali C, Siciliani S, Zannino L, Biggiogera M. Histochemistry for nucleic acid research: 60 years in the European Journal of Histochemistry. Eur J Histochem 2022; 66:3409. [PMID: 35441834 PMCID: PMC9044459 DOI: 10.4081/ejh.2022.3409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 04/07/2022] [Indexed: 11/23/2022] Open
Abstract
Since the discovery of DNA structure in 1953, the deoxyribonucleic acid has always been playing a central role in biological research. As physical and ordered nucleotides sequence, it stands at the base of genes existence. Furthermore, beside this 2-dimensional sequence, DNA is characterized by a 3D structural and functional organization, which is of interest for the scientific community due to multiple levels of expression regulation, of interaction with other biomolecules, and much more. Analogously, the nucleic acid counterpart of DNA, RNA, represents a central issue in research, because of its fundamental role in gene expression and regulation, and for the DNA-RNA interplay. Because of their importance, DNA and RNA have always been mentioned and studied in several publications, and the European Journal of Histochemistry is no exception. Here, we review and discuss the papers published in the last 60 years of this Journal, focusing on its contribution in deepening the knowledge about this topic and analysing papers that reflect the interest this Journal always granted to the world of DNA and RNA.
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Affiliation(s)
- Claudio Casali
- Laboratory of Cell Biology and Neurobiology, Department of Biology and Biotechnology, University of Pavia.
| | - Stella Siciliani
- Laboratory of Cell Biology and Neurobiology, Department of Biology and Biotechnology, University of Pavia.
| | - Lorena Zannino
- Laboratory of Cell Biology and Neurobiology, Department of Biology and Biotechnology, University of Pavia.
| | - Marco Biggiogera
- Laboratory of Cell Biology and Neurobiology, Department of Biology and Biotechnology, University of Pavia.
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3
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Andreana I, Repellin M, Carton F, Kryza D, Briançon S, Chazaud B, Mounier R, Arpicco S, Malatesta M, Stella B, Lollo G. Nanomedicine for Gene Delivery and Drug Repurposing in the Treatment of Muscular Dystrophies. Pharmaceutics 2021; 13:278. [PMID: 33669654 PMCID: PMC7922331 DOI: 10.3390/pharmaceutics13020278] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 02/07/2021] [Accepted: 02/14/2021] [Indexed: 12/11/2022] Open
Abstract
Muscular Dystrophies (MDs) are a group of rare inherited genetic muscular pathologies encompassing a variety of clinical phenotypes, gene mutations and mechanisms of disease. MDs undergo progressive skeletal muscle degeneration causing severe health problems that lead to poor life quality, disability and premature death. There are no available therapies to counteract the causes of these diseases and conventional treatments are administered only to mitigate symptoms. Recent understanding on the pathogenetic mechanisms allowed the development of novel therapeutic strategies based on gene therapy, genome editing CRISPR/Cas9 and drug repurposing approaches. Despite the therapeutic potential of these treatments, once the actives are administered, their instability, susceptibility to degradation and toxicity limit their applications. In this frame, the design of delivery strategies based on nanomedicines holds great promise for MD treatments. This review focuses on nanomedicine approaches able to encapsulate therapeutic agents such as small chemical molecules and oligonucleotides to target the most common MDs such as Duchenne Muscular Dystrophy and the Myotonic Dystrophies. The challenge related to in vitro and in vivo testing of nanosystems in appropriate animal models is also addressed. Finally, the most promising nanomedicine-based strategies are highlighted and a critical view in future developments of nanomedicine for neuromuscular diseases is provided.
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Affiliation(s)
- Ilaria Andreana
- Laboratoire d’Automatique, de Génie des Procédés et de Génie Pharmaceutique, Université Claude Bernard Lyon 1, CNRS UMR 5007, 43 bd 11 Novembre 1918, 69622 Villeurbanne, France; (I.A.); (M.R.); (D.K.); (S.B.)
- Department of Drug Science and Technology, University of Turin, Via P. Giuria 9, 10125 Torino, Italy;
| | - Mathieu Repellin
- Laboratoire d’Automatique, de Génie des Procédés et de Génie Pharmaceutique, Université Claude Bernard Lyon 1, CNRS UMR 5007, 43 bd 11 Novembre 1918, 69622 Villeurbanne, France; (I.A.); (M.R.); (D.K.); (S.B.)
- Department of Neurosciences, Biomedicine and Movement Sciences, Anatomy and Histology Section, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy; (F.C.); (M.M.)
| | - Flavia Carton
- Department of Neurosciences, Biomedicine and Movement Sciences, Anatomy and Histology Section, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy; (F.C.); (M.M.)
- Department of Health Sciences, University of Eastern Piedmont, Via Solaroli 17, 28100 Novara, Italy
| | - David Kryza
- Laboratoire d’Automatique, de Génie des Procédés et de Génie Pharmaceutique, Université Claude Bernard Lyon 1, CNRS UMR 5007, 43 bd 11 Novembre 1918, 69622 Villeurbanne, France; (I.A.); (M.R.); (D.K.); (S.B.)
- Hospices Civils de Lyon, 69437 Lyon, France
| | - Stéphanie Briançon
- Laboratoire d’Automatique, de Génie des Procédés et de Génie Pharmaceutique, Université Claude Bernard Lyon 1, CNRS UMR 5007, 43 bd 11 Novembre 1918, 69622 Villeurbanne, France; (I.A.); (M.R.); (D.K.); (S.B.)
| | - Bénédicte Chazaud
- Institut NeuroMyoGène, University of Lyon, INSERM U1217, CNRS UMR 5310, 8 Avenue Rockefeller, 69008 Lyon, France; (B.C.); (R.M.)
| | - Rémi Mounier
- Institut NeuroMyoGène, University of Lyon, INSERM U1217, CNRS UMR 5310, 8 Avenue Rockefeller, 69008 Lyon, France; (B.C.); (R.M.)
| | - Silvia Arpicco
- Department of Drug Science and Technology, University of Turin, Via P. Giuria 9, 10125 Torino, Italy;
| | - Manuela Malatesta
- Department of Neurosciences, Biomedicine and Movement Sciences, Anatomy and Histology Section, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy; (F.C.); (M.M.)
| | - Barbara Stella
- Department of Drug Science and Technology, University of Turin, Via P. Giuria 9, 10125 Torino, Italy;
| | - Giovanna Lollo
- Laboratoire d’Automatique, de Génie des Procédés et de Génie Pharmaceutique, Université Claude Bernard Lyon 1, CNRS UMR 5007, 43 bd 11 Novembre 1918, 69622 Villeurbanne, France; (I.A.); (M.R.); (D.K.); (S.B.)
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4
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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 PMCID: PMC7081929 DOI: 10.1021/acschembio.9b00958] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [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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5
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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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6
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Thomas JD, Oliveira R, Sznajder ŁJ, Swanson MS. Myotonic Dystrophy and Developmental Regulation of RNA Processing. Compr Physiol 2018; 8:509-553. [PMID: 29687899 PMCID: PMC11323716 DOI: 10.1002/cphy.c170002] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Myotonic dystrophy (DM) is a multisystemic disorder caused by microsatellite expansion mutations in two unrelated genes leading to similar, yet distinct, diseases. DM disease presentation is highly variable and distinguished by differences in age-of-onset and symptom severity. In the most severe form, DM presents with congenital onset and profound developmental defects. At the molecular level, DM pathogenesis is characterized by a toxic RNA gain-of-function mechanism that involves the transcription of noncoding microsatellite expansions. These mutant RNAs disrupt key cellular pathways, including RNA processing, localization, and translation. In DM, these toxic RNA effects are predominantly mediated through the modulation of the muscleblind-like and CUGBP and ETR-3-like factor families of RNA binding proteins (RBPs). Dysfunction of these RBPs results in widespread RNA processing defects culminating in the expression of developmentally inappropriate protein isoforms in adult tissues. The tissue that is the focus of this review, skeletal muscle, is particularly sensitive to mutant RNA-responsive perturbations, as patients display a variety of developmental, structural, and functional defects in muscle. Here, we provide a comprehensive overview of DM1 and DM2 clinical presentation and pathology as well as the underlying cellular and molecular defects associated with DM disease onset and progression. Additionally, fundamental aspects of skeletal muscle development altered in DM are highlighted together with ongoing and potential therapeutic avenues to treat this muscular dystrophy. © 2018 American Physiological Society. Compr Physiol 8:509-553, 2018.
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Affiliation(s)
- James D. Thomas
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, Florida, USA
| | - Ruan Oliveira
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, Florida, USA
| | - Łukasz J. Sznajder
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, Florida, USA
| | - Maurice S. Swanson
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, Florida, USA
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7
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Meola G, Cardani R. Myotonic Dystrophy Type 2: An Update on Clinical Aspects, Genetic and Pathomolecular Mechanism. J Neuromuscul Dis 2015; 2:S59-S71. [PMID: 27858759 PMCID: PMC5240594 DOI: 10.3233/jnd-150088] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Myotonic dystrophy (DM) is the most common adult muscular dystrophy, characterized by autosomal dominant progressive myopathy, myotonia and multiorgan involvement. To date two distinct forms caused by similar mutations have been identified. Myotonic dystrophy type 1 (DM1, Steinert's disease) is caused by a (CTG)n expansion in DMPK, while myotonic dystrophy type 2 (DM2) is caused by a (CCTG)n expansion in CNBP. Despite clinical and genetic similarities, DM1 and DM2 are distinct disorders. The pathogenesis of DM is explained by a common RNA gain-of-function mechanism in which the CUG and CCUG repeats alter cellular function, including alternative splicing of various genes. However additional pathogenic mechanism like changes in gene expression, modifier genes, protein translation and micro-RNA metabolism may also contribute to disease pathology and to clarify the phenotypic differences between these two types of myotonic dystrophies.This review is an update on the latest findings specific to DM2, including explanations for the differences in clinical manifestations and pathophysiology between the two forms of myotonic dystrophies.
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Affiliation(s)
- Giovanni Meola
- Department of Biomedical Sciences for Health, IRCCS Policlinico San Donato, University of Milan, San Donato Milanese, Milan, Italy
- Laboratory of Muscle Histopathology and Molecular Biology, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy
| | - Rosanna Cardani
- Laboratory of Muscle Histopathology and Molecular Biology, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy
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Malatesta M, Cardani R, Pellicciari C, Meola G. RNA Transcription and Maturation in Skeletal Muscle Cells are Similarly Impaired in Myotonic Dystrophy and Sarcopenia: The Ultrastructural Evidence. Front Aging Neurosci 2014; 6:196. [PMID: 25126079 PMCID: PMC4115624 DOI: 10.3389/fnagi.2014.00196] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 07/15/2014] [Indexed: 01/23/2023] Open
Affiliation(s)
- Manuela Malatesta
- Anatomy and Histology Section, Department of Neurological and Movement Sciences, University of Verona , Verona , Italy
| | - Rosanna Cardani
- Laboratory of Muscle Histopathology and Molecular Biology, IRCCS-Policlinico San Donato , Milan , Italy
| | - Carlo Pellicciari
- Laboratory of Cell Biology and Neurobiology, Department of Biology and Biotechnology, University of Pavia , Pavia , Italy
| | - Giovanni Meola
- Laboratory of Muscle Histopathology and Molecular Biology, IRCCS-Policlinico San Donato , Milan , Italy ; Department of Neurology, University of Milan , Milan , Italy
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Meola G, Cardani R. Myotonic dystrophies: An update on clinical aspects, genetic, pathology, and molecular pathomechanisms. Biochim Biophys Acta Mol Basis Dis 2014; 1852:594-606. [PMID: 24882752 DOI: 10.1016/j.bbadis.2014.05.019] [Citation(s) in RCA: 213] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 05/19/2014] [Accepted: 05/20/2014] [Indexed: 01/18/2023]
Abstract
Myotonic dystrophy (DM) is the most common adult muscular dystrophy, characterized by autosomal dominant progressive myopathy, myotonia and multiorgan involvement. To date two distinct forms caused by similar mutations have been identified. Myotonic dystrophy type 1 (DM1, Steinert's disease) is caused by a (CTG)n expansion in DMPK, while myotonic dystrophy type 2 (DM2) is caused by a (CCTG)n expansion in ZNF9/CNBP. When transcribed into CUG/CCUG-containing RNA, mutant transcripts aggregate as nuclear foci that sequester RNA-binding proteins, resulting in spliceopathy of downstream effector genes. However, it is now clear that additional pathogenic mechanism like changes in gene expression, protein translation and micro-RNA metabolism may also contribute to disease pathology. Despite clinical and genetic similarities, DM1 and DM2 are distinct disorders requiring different diagnostic and management strategies. This review is an update on the recent advances in the understanding of the molecular mechanisms behind myotonic dystrophies. This article is part of a Special Issue entitled: Neuromuscular Diseases: Pathology and Molecular Pathogenesis.
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Affiliation(s)
- Giovanni Meola
- Department of Neurology, IRCCS Policlinico San Donato, University of Milan, San Donato Milanese, Milan, Italy; Laboratory of Muscle Histopathology and Molecular Biology, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy.
| | - Rosanna Cardani
- Laboratory of Muscle Histopathology and Molecular Biology, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy.
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Malatesta M, Giagnacovo M, Cardani R, Meola G, Pellicciari C. Human myoblasts from skeletal muscle biopsies: in vitro culture preparations for morphological and cytochemical analyses at light and electron microscopy. Methods Mol Biol 2013; 976:67-79. [PMID: 23400435 DOI: 10.1007/978-1-62703-317-6_6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We describe protocols for the isolation of satellite cells from human muscle biopsies, for the in vitro culture of proliferating and differentiating myoblasts, and for the preparation of cell samples suitable for morphological and cytochemical analyses at light and electron microscopy. The procedures described are especially appropriate for processing small muscle biopsies, and allow obtaining myoblast/myotube monolayers on glass coverslips, thus preserving good cell morphology and immunoreactivity for protein markers of myoblast proliferation, differentiation, and senescence.These cell preparations are suitable for cytochemical, immunocytochemical, and FISH procedures at light microscopy, and can be observed not only in bright field, phase contrast, and differential interference contrast but also in fluorescence (which can hardly be used for cells grown on conventional plastic surfaces, which generally exhibit intense autofluorescence). In their ultrastructural cytochemical application, the protocols are intended for post-embedding techniques, by which ultrathin sections from a single sample may be used for detecting a wide variety of molecular markers.
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Affiliation(s)
- Manuela Malatesta
- Sezione di Anatomia e Istologia, Dipartimento di Scienze Neurologiche, Neuropsicologiche, Morfologiche e Motorie, University of Verona, Verona, Italy.
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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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Nuclear ribonucleoprotein-containing foci increase in size in non-dividing cells from patients with myotonic dystrophy type 2. Histochem Cell Biol 2012; 138:699-707. [PMID: 22706481 DOI: 10.1007/s00418-012-0984-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/04/2012] [Indexed: 10/28/2022]
Abstract
Myotonic dystrophies (DM) are genetically based neuromuscular disorders characterized by the accumulation of mutant transcripts into peculiar intranuclear foci, where different splicing factors (among which the alternative splicing regulator muscleblind-like 1 protein, MBNL1) are ectopically sequestered. The aim of the present investigation was to describe the dynamics of the DM-specific intranuclear foci in interphase nuclei and during mitosis, as well as after the exit from the cell cycle. Primary cultures of skin fibroblasts from DM2 patients were used, as a model system to reproduce in vitro, as accurately as possible, the in vivo conditions. Cycling and resting fibroblasts were investigated by immunocytochemical and morphometric techniques, and the relative amounts of MBNL1 were also estimated by western blotting. MBNL1-containing foci were exclusively found in the nucleus during most of the interphase, while being observed in the cytoplasm during mitosis when they never associate with the chromosomes; the foci remained in the cytoplasm at cytodieresis, and underwent disassembly in early G1 to be reformed in the nucleus at each cell cycle. After fibroblasts had stopped dividing in late-passage cultures, the nuclear foci were observed to progressively increase in size. Interestingly, measurements on muscle biopsies taken from the same DM2 patients at different ages demonstrated that, in the nuclei of myofibers, the MBNL1-containing foci become larger with increasing patient's age. As a whole, these results suggest that in non-dividing cells of DM2 patients the sequestration in the nuclear foci of factors needed for RNA processing would be continuous and progressive, eventually leading to the onset (and the worsening with time) of the pathological traits. This is consistent with the evidence that in DM patients the most affected organs or tissues are those where non-renewing cells are mainly present, i.e., the central nervous system, heart and skeletal muscle.
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Wojciechowska M, Krzyzosiak WJ. Cellular toxicity of expanded RNA repeats: focus on RNA foci. Hum Mol Genet 2011; 20:3811-21. [PMID: 21729883 PMCID: PMC3168290 DOI: 10.1093/hmg/ddr299] [Citation(s) in RCA: 177] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Discrete and punctate nuclear RNA foci are characteristic molecular hallmarks of pathogenesis in myotonic dystrophy type 1 and type 2. Intranuclear RNA inclusions of distinct morphology have also been found in fragile X-associated tremor ataxia syndrome, Huntington's disease-like 2, spinocerebellar ataxias type 8, type 10 and type 31. These neurological diseases are associated with the presence of abnormally long simple repeat expansions in their respective genes whose expression leads to the formation of flawed transcripts with altered metabolisms. Expanded CUG, CCUG, CGG, CAG, AUUCU and UGGAA repeats are associated with the diseases and accumulate in nuclear foci, as demonstrated in variety of cells and tissues of human and model organisms. These repeat RNA foci differ in size, shape, cellular abundance and protein composition and their formation has a negative impact on cellular functions. This review summarizes the efforts of many laboratories over the past 15 years to characterize nuclear RNA foci that are recognized as important triggers in the mutant repeat RNA toxic gain-of-function mechanisms of pathogenesis in neurological disorders.
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Affiliation(s)
- Marzena Wojciechowska
- Laboratory of Cancer Genetics, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland
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14
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Malatesta M, Giagnacovo M, Cardani R, Meola G, Pellicciari C. RNA processing is altered in skeletal muscle nuclei of patients affected by myotonic dystrophy. Histochem Cell Biol 2011; 135:419-25. [PMID: 21387185 DOI: 10.1007/s00418-011-0797-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/18/2011] [Indexed: 01/07/2023]
Abstract
Myotonic dystrophies (DMs) are characterised by highly variable clinical manifestations consisting of muscle weakness and atrophy, and a wide spectrum of extramuscular manifestations. In both DM1 and DM2 forms, expanded nucleotide sequences cause the accumulation of mutant transcripts in the nucleus, thus deregulating the function of some RNA-binding proteins and providing a plausible explanation for the multifactorial phenotype of DM patients. However, at the skeletal muscle level, no mechanistic explanation for the muscle wasting has so far been proposed. We therefore performed a study in situ by immunoelectron microscopy on biceps brachii biopsies from DM1, DM2 and healthy subjects, providing the first ultrastructural evidence on the distribution of some nuclear ribonucleoprotein (RNP)-containing structures and molecular factors involved in pre-mRNA transcription and maturation in dystrophic myonuclei. Our results demonstrated an accumulation of splicing and cleavage factors in myonuclei of both DM1 and DM2 patients, suggesting an impairment of post-transcriptional pre-mRNA pathways. The transcription of the expanded sequences in DM myonuclei would therefore hamper functionality of the whole splicing machinery, slowing down the intranuclear molecular trafficking; this would reduce the capability of myonuclei to respond to anabolic stimuli thus contributing to muscle wasting.
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Affiliation(s)
- Manuela Malatesta
- Dipartimento di Scienze Neurologiche, Neuropsicologiche, Morfologiche e Motorie, Sezione di Anatomia e Istologia, Università di Verona, Verona, Italy
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15
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Muscular dystrophies: an update on pathology and diagnosis. Acta Neuropathol 2010; 120:343-58. [PMID: 20652576 DOI: 10.1007/s00401-010-0727-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 07/09/2010] [Accepted: 07/12/2010] [Indexed: 12/31/2022]
Abstract
Muscular dystrophies are clinically, genetically, and molecularly a heterogeneous group of neuromuscular disorders. Considerable advances have been made in recent years in the identification of causative genes, the differentiation of the different forms and in broadening the understanding of pathogenesis. Muscle pathology has an important role in these aspects, but correlation of the pathology with clinical phenotype is essential. Immunohistochemistry has a major role in differential diagnosis, particularly in recessive forms where an absence or reduction in protein expression can be detected. Several muscular dystrophies are caused by defects in genes encoding sarcolemmal proteins, several of which are known to interact. Others are caused by defects in nuclear membrane proteins or enzymes. Assessment of both primary and secondary abnormalities in protein expression is useful, in particular the hypoglycosylation of alpha-dystroglycan. In dominantly inherited muscular dystrophies it is rarely possible to detect a change in the expression of the primary defective protein; an exception to this is caveolin-3.
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