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Lee EJ, Kim AY, Lee EM, Lee MM, Min CW, Kang KK, Park JK, Hwang M, Kwon SH, Tremblay JP, Jeong KS. Therapeutic effects of exon skipping and losartan on skeletal muscle of mdx mice. Pathol Int 2015; 64:388-96. [PMID: 25143127 DOI: 10.1111/pin.12190] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 07/05/2014] [Indexed: 12/22/2022]
Abstract
Various attempts have been made to find treatments for Duchenne muscular dystrophy (DMD) patients. Exon skipping is one of the promising technologies for DMD treatment by restoring dystropin protein, which is one of the muscle components. It is well known that losartan, an angiotensin II type1 receptor blocker, promotes muscle regeneration and differentiation by lowering the level of transforming growth factor-beta1 signaling. In this study, we illustrated the combined effects of exon skipping and losartan on skeletal muscle of mdx mice. We supplied mdx mice with losartan for 2 weeks before exon skipping treatment. The losartan with the exon skipping group showed less expression of myf5 than the losartan treated group. Also the losartan with exon skipping group recovered normal muscle architecture, in contrast to the losartan group which still showed many central nuclei. However, the exon skipping efficiency and the restoration of dystrophin protein were lower in the losartan with exon skipping group compared to the exon skipping group. We reveal that losartan promotes muscle regeneration and shortens the time taken to restore normal muscle structure when combined with exon skipping. However, combined treatment of exon skipping and losartan decreases the restoration of dystrophin protein meaning decrease of exon skipping efficiency.
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Affiliation(s)
- Eun-Joo Lee
- College of Veterinary Medicine, School of Medicine, Kyungpook National University, Daegu, Korea; Stem Cell Therapeutic Research Institute, School of Medicine, Kyungpook National University, Daegu, Korea
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52
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Brancaccio A, Palacios D. Chromatin signaling in muscle stem cells: interpreting the regenerative microenvironment. Front Aging Neurosci 2015; 7:36. [PMID: 25904863 PMCID: PMC4387924 DOI: 10.3389/fnagi.2015.00036] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 03/04/2015] [Indexed: 12/12/2022] Open
Abstract
Muscle regeneration in the adult occurs in response to damage at expenses of a population of adult stem cells, the satellite cells. Upon injury, either physical or genetic, signals released within the satellite cell niche lead to the commitment, expansion and differentiation of the pool of muscle progenitors to repair damaged muscle. To achieve this goal satellite cells undergo a dramatic transcriptional reprogramming to coordinately activate and repress specific subset of genes. Although the epigenetics of muscle regeneration has been extensively discussed, less emphasis has been put on how extra-cellular cues are translated into the specific chromatin reorganization necessary for progression through the myogenic program. In this review we will focus on how satellite cells sense the regenerative microenvironment in physiological and pathological circumstances, paying particular attention to the mechanism through which the external stimuli are transduced to the nucleus to modulate chromatin structure and gene expression. We will discuss the pathways involved and how alterations in this chromatin signaling may contribute to satellite cells dysfunction during aging and disease.
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Affiliation(s)
- Arianna Brancaccio
- Laboratory of Epigenetics and Signaling, IRCCS Fondazione Santa Lucia Rome, Italy
| | - Daniela Palacios
- Laboratory of Epigenetics and Signaling, IRCCS Fondazione Santa Lucia Rome, Italy
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53
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H19 long noncoding RNA controls the mRNA decay promoting function of KSRP. Proc Natl Acad Sci U S A 2014; 111:E5023-8. [PMID: 25385579 DOI: 10.1073/pnas.1415098111] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Long noncoding RNAs (lncRNAs) interact with protein factors to regulate different layers of gene expression transcriptionally or posttranscriptionally. Here we report on the functional consequences of the unanticipated interaction of the RNA binding protein K homology-type splicing regulatory protein (KSRP) with the H19 lncRNA (H19). KSRP directly binds to H19 in the cytoplasm of undifferentiated multipotent mesenchymal C2C12 cells, and this interaction favors KSRP-mediated destabilization of labile transcripts such as myogenin. AKT activation induces KSRP dismissal from H19 and, as a consequence, myogenin mRNA is stabilized while KSRP is repurposed to promote maturation of myogenic microRNAs, thus favoring myogenic differentiation. Our data indicate that H19 operates as a molecular scaffold that facilitates effective association of KSRP with myogenin and other labile transcripts, and we propose that H19 works with KSRP to optimize an AKT-regulated posttranscriptional switch that controls myogenic differentiation.
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Segalés J, Perdiguero E, Muñoz-Cánoves P. Epigenetic control of adult skeletal muscle stem cell functions. FEBS J 2014; 282:1571-88. [PMID: 25251895 DOI: 10.1111/febs.13065] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 09/18/2014] [Accepted: 09/19/2014] [Indexed: 12/12/2022]
Abstract
Skeletal muscle regeneration in the adult (de novo myogenesis) depends on a resident population of muscle stem cells (satellite cells) that are normally quiescent. In response to injury or stress, satellite cells are activated and expand as myoblast cells that differentiate and fuse to form new muscle fibers or return to quiescence to maintain the stem cell pool (self-renewal). Satellite cell-dependent myogenesis is a well-characterized multi-step process orchestrated by muscle-specific transcription factors, such as Pax3/Pax7 and members of the MyoD family of muscle regulatory factors, and epigenetically controlled by mechanisms such as DNA methylation, covalent modification of histones and non-coding RNAs. Recent results from next-generation genome-wide sequencing have increased our understanding about the highly intricate layers of epigenetic regulation involved in satellite cell maintenance, activation, differentiation and self-renewal, and their cross-talk with the muscle-specific transcriptional machinery.
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Affiliation(s)
- Jessica Segalés
- Cell Biology Group, Department of Experimental and Health Sciences, Pompeu Fabra University, Center for Networked Biomedical Research on Neurodegenerative Diseases, Barcelona, Spain
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55
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Joliot V, Ait-Mohamed O, Battisti V, Pontis J, Philipot O, Robin P, Ito H, Ait-Si-Ali S. The SWI/SNF subunit/tumor suppressor BAF47/INI1 is essential in cell cycle arrest upon skeletal muscle terminal differentiation. PLoS One 2014; 9:e108858. [PMID: 25271443 PMCID: PMC4182762 DOI: 10.1371/journal.pone.0108858] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 08/26/2014] [Indexed: 12/22/2022] Open
Abstract
Myogenic terminal differentiation is a well-orchestrated process starting with permanent cell cycle exit followed by muscle-specific genetic program activation. Individual SWI/SNF components have been involved in muscle differentiation. Here, we show that the master myogenic differentiation factor MyoD interacts with more than one SWI/SNF subunit, including the catalytic subunit BRG1, BAF53a and the tumor suppressor BAF47/INI1. Downregulation of each of these SWI/SNF subunits inhibits skeletal muscle terminal differentiation but, interestingly, at different differentiation steps and extents. BAF53a downregulation inhibits myotube formation but not the expression of early muscle-specific genes. BRG1 or BAF47 downregulation disrupt both proliferation and differentiation genetic programs expression. Interestingly, BRG1 and BAF47 are part of the SWI/SNF remodeling complex as well as the N-CoR-1 repressor complex in proliferating myoblasts. However, our data show that, upon myogenic differentiation, BAF47 shifts in favor of N-CoR-1 complex. Finally, BRG1 and BAF47 are well-known tumor suppressors but, strikingly, only BAF47 seems essential in the myoblasts irreversible cell cycle exit. Together, our data unravel differential roles for SWI/SNF subunits in muscle differentiation, with BAF47 playing a dual role both in the permanent cell cycle exit and in the regulation of muscle-specific genes.
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Affiliation(s)
- Véronique Joliot
- Université Paris Diderot, Sorbonne Paris Cité, Centre Epigénétique et Destin Cellulaire, UMR7216, Centre National de la Recherche Scientifique CNRS, Université Paris Diderot, Paris, France
| | - Ouardia Ait-Mohamed
- Université Paris Diderot, Sorbonne Paris Cité, Centre Epigénétique et Destin Cellulaire, UMR7216, Centre National de la Recherche Scientifique CNRS, Université Paris Diderot, Paris, France
| | - Valentine Battisti
- Université Paris Diderot, Sorbonne Paris Cité, Centre Epigénétique et Destin Cellulaire, UMR7216, Centre National de la Recherche Scientifique CNRS, Université Paris Diderot, Paris, France
| | - Julien Pontis
- Université Paris Diderot, Sorbonne Paris Cité, Centre Epigénétique et Destin Cellulaire, UMR7216, Centre National de la Recherche Scientifique CNRS, Université Paris Diderot, Paris, France
| | - Ophélie Philipot
- Université Paris Diderot, Sorbonne Paris Cité, Centre Epigénétique et Destin Cellulaire, UMR7216, Centre National de la Recherche Scientifique CNRS, Université Paris Diderot, Paris, France
| | - Philippe Robin
- Université Paris Diderot, Sorbonne Paris Cité, Centre Epigénétique et Destin Cellulaire, UMR7216, Centre National de la Recherche Scientifique CNRS, Université Paris Diderot, Paris, France
| | - Hidenori Ito
- Department of Molecular Neurobiology, Institute for Developmental Research, Aichi Human Service Center, Aichi, Japan
| | - Slimane Ait-Si-Ali
- Université Paris Diderot, Sorbonne Paris Cité, Centre Epigénétique et Destin Cellulaire, UMR7216, Centre National de la Recherche Scientifique CNRS, Université Paris Diderot, Paris, France
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56
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Differential effects of short-term β agonist and growth hormone treatments on expression of myosin heavy chain IIB and associated metabolic genes in sheep muscle. Animal 2014; 9:285-94. [PMID: 25213627 PMCID: PMC4299534 DOI: 10.1017/s175173111400233x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Growth hormone (GH) and β agonists increase muscle mass, but the mechanisms for this response are unclear and the magnitude of response is thought to vary with age of animal. To investigate the mechanisms driving the muscle response to these agents, we examined the effects of short-term (6 day) administration of GH or cimaterol (a β2-adrenergic agonist, BA) on skeletal muscle phenotype in both young (day 60) and mature (day 120) lambs. Expression of myosin heavy chain (MyHC) isoforms were measured in Longissimus dorsi (LD), Semitendinosus (ST) and Supraspinatus (SS) muscles as markers of fibre type and metabolic enzyme activities were measured in LD. To investigate potential mechanisms regulating the changes in fibre type/metabolism, expression or activity of a number of signalling molecules were examined in LD. There were no effects of GH administration on MyHC isoform expression at either the mRNA or protein level in any of the muscles. However, BA treatment induced a proportional change in MyHC mRNA expression at both ages, with the %MyHCI and/or IIA mRNA being significantly decreased in all three muscles and %MyHCIIX/IIB mRNA significantly increased in the LD and ST. BA treatment induced de novo expression of MyHCIIB mRNA in LD, the fastest isoform not normally expressed in sheep LD, as well as increasing expression in the other two muscles. In the LD, the increased expression of the fastest MyHC isoforms (IIX and IIB) was associated with a decrease in isocitrate dehydrogenase activity, but no change in lactate dehydrogenase activity, indicating a reduced capacity for oxidative metabolism. In both young and mature lambs, changes in expression of metabolic regulatory factors were observed that might induce these changes in muscle metabolism/fibre type. In particular, BA treatment decreased PPAR-γ coactivator-1β mRNA and increased receptor-interacting protein 140 mRNA. The results suggest that the two agents work via different mechanisms or over different timescales, with only BA inducing changes in muscle mass and transitions to a faster, less oxidative fibre type after a 6-day treatment.
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57
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Shimizu K, Uematsu A, Imai Y, Sawasaki T. Pctaire1/Cdk16 promotes skeletal myogenesis by inducing myoblast migration and fusion. FEBS Lett 2014; 588:3030-7. [PMID: 24931367 DOI: 10.1016/j.febslet.2014.05.060] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 05/29/2014] [Accepted: 05/29/2014] [Indexed: 01/17/2023]
Abstract
The Cdk-related protein kinase Pctaire1/Cdk16 is abundantly expressed in brain, testis and skeletal muscle. Functional roles of Pctaire1 such as regulation of neuron migration and neurite outgrowth thus far have been mainly elucidated in the field of nervous system development. Although these regulations based on cytoskeletal rearrangements evoke a possible role of Pctaire1 in the development of skeletal muscle, little is known in this regard. In this study, we demonstrated that myogenic differentiation and subsequent fusion is promoted in Pctaire1 overexpressing cells, and conversely, is inhibited in the knockdown cells. Furthermore, our findings suggest that Pctaire1 exerts promyogenic effects by regulating myoblast migration and process formation during skeletal myogenesis.
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Affiliation(s)
- Kouhei Shimizu
- Division of Cell-Free Sciences, Proteo-Science Center, Ehime University, Matsuyama 790-8577, Japan
| | - Atsushi Uematsu
- Division of Cell-Free Sciences, Proteo-Science Center, Ehime University, Matsuyama 790-8577, Japan
| | - Yuuki Imai
- Division of Integrative Pathophysiology, Proteo-Science Center, Graduate School of Medicine, Ehime University, Toon 791-0295, Japan
| | - Tatsuya Sawasaki
- Division of Cell-Free Sciences, Proteo-Science Center, Ehime University, Matsuyama 790-8577, Japan; The Venture Business Laboratory, Ehime University, Matsuyama 790-8577, Japan.
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58
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Marchesi I, Giordano A, Bagella L. Roles of enhancer of zeste homolog 2: from skeletal muscle differentiation to rhabdomyosarcoma carcinogenesis. Cell Cycle 2014; 13:516-27. [PMID: 24496329 DOI: 10.4161/cc.27921] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Polycomb group proteins represent a global silencing system involved in embryonic development and stem-cell maintenance that regulates the transition from proliferation to differentiation during organogenesis. Two main complexes have been discovered: the polycomb repressive complex (PRC) 1 and 2, able to induce gene silencing by a synergistic mechanism or independently by each other. Enhancer of zeste homolog 2 (EZH2), the catalytic subunit of PRC2, represses gene transcription through the tri-methylation of histone H3 lysine 27. EZH2 deregulation is frequently associated with tumorigenesis, metastatic character, and poor prognosis in various cancer types. This review explores the role of EZH2 in normal development and in carcinogenesis. We reviewed the polycomb-mediated silencing mechanisms, the regulation of EZH2 activity and its recruitment to target genes. We also analyzed the role of EZH2 in normal muscle differentiation and in rhabdomyosarcoma, considering EZH2 blockade as a new strategy for developing specific therapies.
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Affiliation(s)
- Irene Marchesi
- Department of Biomedical Sciences; Division of Biochemistry and National Institute of Biostructures and Biosystems; University of Sassari; Sassari, Italy
| | - Antonio Giordano
- Sbarro Institute for Cancer Research and Molecular Medicine; Center for Biotechnology; College of Science and Technology; Temple University; Philadelphia, PA USA; Human Pathology and Oncology Department; University of Siena; Siena, Italy
| | - Luigi Bagella
- Department of Biomedical Sciences; Division of Biochemistry and National Institute of Biostructures and Biosystems; University of Sassari; Sassari, Italy; Sbarro Institute for Cancer Research and Molecular Medicine; Center for Biotechnology; College of Science and Technology; Temple University; Philadelphia, PA USA
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59
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Sobrian SK, Walters E. Enhanced Satellite Cell Activity in Aging Skeletal Muscle after Manual Acupuncture-Induced Injury. Chin Med 2014. [DOI: 10.4236/cm.2014.51004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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60
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Abstract
Since the seminal discovery of the cell-fate regulator Myod, studies in skeletal myogenesis have inspired the search for cell-fate regulators of similar potential in other tissues and organs. It was perplexing that a similar transcription factor for other tissues was not found; however, it was later discovered that combinations of molecular regulators can divert somatic cell fates to other cell types. With the new era of reprogramming to induce pluripotent cells, the myogenesis paradigm can now be viewed under a different light. Here, we provide a short historical perspective and focus on how the regulation of skeletal myogenesis occurs distinctly in different scenarios and anatomical locations. In addition, some interesting features of this tissue underscore the importance of reconsidering the simple-minded view that a single stem cell population emerges after gastrulation to assure tissuegenesis. Notably, a self-renewing long-term Pax7+ myogenic stem cell population emerges during development only after a first wave of terminal differentiation occurs to establish a tissue anlagen in the mouse. How the future stem cell population is selected in this unusual scenario will be discussed. Recently, a wealth of information has emerged from epigenetic and genome-wide studies in myogenic cells. Although key transcription factors such as Pax3, Pax7, and Myod regulate only a small subset of genes, in some cases their genomic distribution and binding are considerably more promiscuous. This apparent nonspecificity can be reconciled in part by the permissivity of the cell for myogenic commitment, and also by new roles for some of these regulators as pioneer transcription factors acting on chromatin state.
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Affiliation(s)
- Glenda Comai
- Stem Cells and Development, CNRS URA 2578, Department of Developmental & Stem Cell Biology, Institut Pasteur, Paris, France
| | - Shahragim Tajbakhsh
- Stem Cells and Development, CNRS URA 2578, Department of Developmental & Stem Cell Biology, Institut Pasteur, Paris, France.
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61
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Andrikou C, Iovene E, Rizzo F, Oliveri P, Arnone MI. Myogenesis in the sea urchin embryo: the molecular fingerprint of the myoblast precursors. EvoDevo 2013; 4:33. [PMID: 24295205 PMCID: PMC4175510 DOI: 10.1186/2041-9139-4-33] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 10/02/2013] [Indexed: 01/01/2023] Open
Abstract
Background In sea urchin larvae the circumesophageal fibers form a prominent muscle system of mesodermal origin. Although the morphology and later development of this muscle system has been well-described, little is known about the molecular signature of these cells or their precise origin in the early embryo. As an invertebrate deuterostome that is more closely related to the vertebrates than other commonly used model systems in myogenesis, the sea urchin fills an important phylogenetic gap and provides a unique perspective on the evolution of muscle cell development. Results Here, we present a comprehensive description of the development of the sea urchin larval circumesophageal muscle lineage beginning with its mesodermal origin using high-resolution localization of the expression of several myogenic transcriptional regulators and differentiation genes. A few myoblasts are bilaterally distributed at the oral vegetal side of the tip of the archenteron and first appear at the late gastrula stage. The expression of the differentiation genes Myosin Heavy Chain, Tropomyosin I and II, as well as the regulatory genes MyoD2, FoxF, FoxC, FoxL1, Myocardin, Twist, and Tbx6 uniquely identify these cells. Interestingly, evolutionarily conserved myogenic factors such as Mef2, MyoR and Six1/2 are not expressed in sea urchin myoblasts but are found in other mesodermal domains of the tip of the archenteron. The regulatory states of these domains were characterized in detail. Moreover, using a combinatorial analysis of gene expression we followed the development of the FoxF/FoxC positive cells from the onset of expression to the end of gastrulation. Our data allowed us to build a complete map of the Non-Skeletogenic Mesoderm at the very early gastrula stage, in which specific molecular signatures identify the precursors of different cell types. Among them, a small group of cells within the FoxY domain, which also express FoxC and SoxE, have been identified as plausible myoblast precursors. Together, these data support a very early gastrula stage segregation of the myogenic lineage. Conclusions From this analysis, we are able to precisely define the regulatory and differentiation signatures of the circumesophageal muscle in the sea urchin embryo. Our findings have important implications in understanding the evolution of development of the muscle cell lineage at the molecular level. The data presented here suggest a high level of conservation of the myogenic specification mechanisms across wide phylogenetic distances, but also reveal clear cases of gene cooption.
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Affiliation(s)
| | | | | | | | - Maria Ina Arnone
- Cellular and Developmental Biology, Stazione Zoologica Anton Dohrn, Napoli 80121, Italy.
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62
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Follo MY, Faenza I, Piazzi M, Blalock WL, Manzoli L, McCubrey JA, Cocco L. Nuclear PI-PLCβ1: an appraisal on targets and pathology. Adv Biol Regul 2013; 54:2-11. [PMID: 24296032 DOI: 10.1016/j.jbior.2013.11.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Accepted: 11/08/2013] [Indexed: 11/16/2022]
Abstract
Lipid signalling molecules are essential components of the processes that allow one extracellular signal to be transferred inside the nucleus, where specific lipid second messengers elicit reactions capable of regulating gene transcription, DNA replication or repair and DNA cleavage, eventually resulting in cell growth, differentiation, apoptosis or many other cell functions. Nuclear inositides are independently regulated, suggesting that the nucleus constitutes a functionally distinct compartment of inositol lipids metabolism. Indeed, nuclear inositol lipids themselves can modulate nuclear processes, such as transcription and pre-mRNA splicing, growth, proliferation, cell cycle regulation and differentiation. Nuclear PI-PLCβ1 is a key molecule for nuclear inositide signalling, where it plays a role in cell cycle progression, proliferation and differentiation. Here we review the targets and possible involvement of nuclear PI-PLCβ1 in human physiology and pathology.
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Affiliation(s)
- Matilde Y Follo
- Department of Biomedical and Neuromotor Sciences, Cellular Signalling Laboratory, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy.
| | - Irene Faenza
- Department of Biomedical and Neuromotor Sciences, Cellular Signalling Laboratory, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Manuela Piazzi
- Department of Biomedical and Neuromotor Sciences, Cellular Signalling Laboratory, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - William L Blalock
- CNR - Consiglio Nazionale delle Ricerche, Istituto di Genetica Molecolare and SC Laboratorio di Biologia Cellulare Muscoloscheletrica, IOR, Bologna, Italy
| | - Lucia Manzoli
- Department of Biomedical and Neuromotor Sciences, Cellular Signalling Laboratory, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - James A McCubrey
- Department of Microbiology and Immunology, Brody School of Medicine at East Carolina University, Greenville, NC, USA
| | - Lucio Cocco
- Department of Biomedical and Neuromotor Sciences, Cellular Signalling Laboratory, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy.
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63
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DNA damage-activated ABL-MyoD signaling contributes to DNA repair in skeletal myoblasts. Cell Death Differ 2013; 20:1664-74. [PMID: 24056763 DOI: 10.1038/cdd.2013.118] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 05/22/2013] [Accepted: 06/21/2013] [Indexed: 12/11/2022] Open
Abstract
Previous works have established a unique function of MyoD in the control of muscle gene expression during DNA damage response in myoblasts. Phosphorylation by DNA damage-activated ABL tyrosine kinase transiently inhibits MyoD-dependent activation of transcription in response to genotoxic stress. We show here that ABL-MyoD signaling is also an essential component of the DNA repair machinery in myoblasts exposed to genotoxic stress. DNA damage promoted the recruitment of MyoD to phosphorylated Nbs1 (pNbs1)-containing repair foci, and this effect was abrogated by either ABL knockdown or the ABL kinase inhibitor imatinib. Upon DNA damage, MyoD and pNbs1 were detected on the chromatin to MyoD target genes without activating transcription. DNA damage-mediated tyrosine phosphorylation was required for MyoD recruitment to target genes, as the ABL phosphorylation-resistant MyoD mutant (MyoD Y30F) failed to bind the chromatin following DNA damage, while retaining the ability to activate transcription in response to differentiation signals. Moreover, MyoD Y30F exhibited an impaired ability to promote repair in a heterologous system, as compared with MyoD wild type (WT). Consistently, MyoD-null satellite cells (SCs) displayed impaired DNA repair that was rescued by reintroduction of MyoD WT but not by MyoD Y30F. In addition, inhibition of ABL kinase prevented MyoD WT-mediated rescue of DNA repair in MyoD-null SCs. These results identify an unprecedented contribution of MyoD to DNA repair and suggest that ABL-MyoD signaling coordinates DNA repair and transcription in myoblasts.
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64
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Liu CZ, Li JJ, Su JM, Jiao T, Gou LJ, He XD, Chang YS. Expression of microRNA-29b2-c Cluster is Positively Regulated by MyoD in L6 Cells. ACTA ACUST UNITED AC 2013; 28:140-6. [DOI: 10.1016/s1001-9294(13)60039-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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65
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Keller C, Guttridge DC. Mechanisms of impaired differentiation in rhabdomyosarcoma. FEBS J 2013; 280:4323-34. [PMID: 23822136 DOI: 10.1111/febs.12421] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 06/17/2013] [Accepted: 07/01/2013] [Indexed: 12/22/2022]
Abstract
Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma of childhood, with presumed skeletal muscle origins, because of its myogenic phenotype. RMS is composed of two main subtypes, embryonal RMS (eRMS) and alveolar RMS (aRMS). Whereas eRMS histologically resembles embryonic skeletal muscle, the aRMS subtype is more aggressive and has a poorer prognosis. In addition, whereas the genetic profile of eRMS is not well established, aRMS is commonly associated with distinct chromosome translocations that fuse domains of the transcription factors Pax3 and Pax7 to the forkhead family member FOXO1A. Both eRMS and aRMS tumor cells express myogenic markers such as MyoD, but their ability to complete differentiation is impaired. How this impairment occurs is the subject of this review, which will focus on several themes, including signaling pathways that converge on Pax-forkhead gene targets, alterations in MyoD function, epigenetic modifications of myogenic promoters, and microRNAs whose expression patterns in RMS alter key regulatory circuits to help maintain tumor cells in an opportunistically less differentiated state.
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Affiliation(s)
- Charles Keller
- Pediatric Cancer Biology Program, Papé Family Pediatric Research Institute, Department of Pediatrics, Oregon Health & Science University, Portland, OR, USA
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66
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Giordani L, Puri PL. Epigenetic control of skeletal muscle regeneration: Integrating genetic determinants and environmental changes. FEBS J 2013; 280:4014-25. [PMID: 23745685 DOI: 10.1111/febs.12383] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 06/04/2013] [Accepted: 06/06/2013] [Indexed: 12/13/2022]
Abstract
During embryonic development, pluripotent cells are genetically committed to specific lineages by the expression of cell-type-specific transcriptional activators that direct the formation of specialized tissues and organs in response to developmental cues. Chromatin-modifying proteins are emerging as essential components of the epigenetic machinery, which establishes the nuclear landscape that ultimately determines the final identity and functional specialization of adult cells. Recent evidence has revealed that discrete populations of adult cells can retain the ability to adopt alternative cell fates in response to environmental cues. These cells include conventional adult stem cells and a still poorly defined collection of cell types endowed with facultative phenotype and functional plasticity. Under physiological conditions or adaptive states, these cells cooperate to support tissue and organ homeostasis, and to promote growth or compensatory regeneration. However, during chronic diseases and aging these cells can adopt a pathological phenotype and mediate maladaptive responses, such as the formation of fibrotic scars and fat deposition that progressively replaces structural and functional units of tissues and organs. The molecular determinants of these phenotypic transitions are only emerging from recent studies that reveal how dynamic chromatin states can generate flexible epigenetic landscapes, which confer on cells the ability to retain partial pluripotency and adapt to environmental changes. This review summarizes our current knowledge on the role of the epigenetic machinery as a 'filter' between genetic commitment and environmental signals in cell types that can alternatively promote skeletal muscle regeneration or fibro-adipogenic degeneration.
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Affiliation(s)
- Lorenzo Giordani
- Sanford-Burnham Medical Research Institute, Sanford Children's Health Research Center, La Jolla, CA, USA
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67
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Guo RM, Xu WM, Lin JC, Mo LQ, Hua XX, Chen PX, Wu K, Zheng DD, Feng JQ. Activation of the p38 MAPK/NF-κB pathway contributes to doxorubicin-induced inflammation and cytotoxicity in H9c2 cardiac cells. Mol Med Rep 2013; 8:603-8. [PMID: 23807148 DOI: 10.3892/mmr.2013.1554] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2013] [Accepted: 06/18/2013] [Indexed: 11/06/2022] Open
Abstract
A number of studies have demonstrated that inflammation plays a role in doxorubicin (DOX)-induced cardiotoxicity. However, the molecular mechanism by which DOX induces cardiac inflammation has yet to be fully elucidated. The present study aimed to investigate the role of the p38 mitogen-activated protein kinase (MAPK)/nuclear factor-κB (NF-κB) pathway in DOX-induced inflammation and cytotoxicity. The results of our study demonstrated that the exposure of H9c2 cardiac cells to DOX reduced cell viability and stimulated an inflammatory response, as demonstrated by an increase in the levels of interleukin-1β (IL-1β) and IL-6, as well as tumor necrosis factor-α (TNF-α) production. Notably, DOX exposure induced the overexpression of phosphorylated p38 MAPK and phosphorylation of the NF-κB p65 subunit, which was markedly inhibited by SB203580, a specific inhibitor of p38 MAPK. The inhibition of NF-κB by pyrrolidine dithiocarbamate (PDTC), a selective inhibitor of NF-κB, significantly ameliorated DOX-induced inflammation, leading to a decrease in the levels of IL-1β and IL-6, as well as TNF-α production in H9c2 cells. The pretreatment of H9c2 cells with either SB203580 or PDTC before exposure to DOX significantly attenuated DOX-induced cytotoxicity. In conclusion, our study provides novel data demonstrating that the p38 MAPK/NF-κB pathway is important in the induction of DOX-induced inflammation and cytotoxicity in H9c2 cardiac myocytes.
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Affiliation(s)
- Run-Min Guo
- Department of Physiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, P.R. China
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68
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Muñoz-Cánoves P, Scheele C, Pedersen BK, Serrano AL. Interleukin-6 myokine signaling in skeletal muscle: a double-edged sword? FEBS J 2013; 280:4131-48. [PMID: 23663276 PMCID: PMC4163639 DOI: 10.1111/febs.12338] [Citation(s) in RCA: 487] [Impact Index Per Article: 44.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 04/25/2013] [Accepted: 05/07/2013] [Indexed: 12/19/2022]
Abstract
Interleukin (IL)-6 is a cytokine with pleiotropic functions in different tissues and organs. Skeletal muscle produces and releases significant levels of IL-6 after prolonged exercise and is therefore considered as a myokine. Muscle is also an important target of the cytokine. IL-6 signaling has been associated with stimulation of hypertrophic muscle growth and myogenesis through regulation of the proliferative capacity of muscle stem cells. Additional beneficial effects of IL-6 include regulation of energy metabolism, which is related to the capacity of actively contracting muscle to synthesize and release IL-6. Paradoxically, deleterious actions for IL-6 have also been proposed, such as promotion of atrophy and muscle wasting. We review the current evidence for these apparently contradictory effects, the mechanisms involved and discuss their possible biological implications.
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Affiliation(s)
- Pura Muñoz-Cánoves
- Cell Biology Group, Department of Experimental and Health Sciences, Pompeu Fabra University (UPF), Institució Catalana de Recerca i Estudis Avançats (ICREA), CIBER on Neurodegenerative diseases (CIBERNED), Barcelona, Spain.
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69
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Shimizu K, Sawasaki T. Nek5, a novel substrate for caspase-3, promotes skeletal muscle differentiation by up-regulating caspase activity. FEBS Lett 2013; 587:2219-25. [PMID: 23727203 DOI: 10.1016/j.febslet.2013.05.049] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 04/23/2013] [Accepted: 05/20/2013] [Indexed: 10/26/2022]
Abstract
Accumulating evidence suggests that caspase-3-mediated cleavage of protein kinase could be a key event to regulate cell differentiation. In this study, we investigated the role of Nek5 kinase, identified as a novel substrate for caspase-3, in skeletal muscle differentiation. Up-regulation of Nek5 mRNA expression was accompanied by cell differentiation. Myotube formation was promoted in Nek5 expressing cells, and was conversely inhibited in Nek5 knockdown cells. Furthermore, we found that caspase-3 activity, an important factor for myogenic differentiation, was enhanced by Nek5 cleavage. Although caspase-3-cleaved Nek5 partially exerted a promyogenic effect, it tended to induce apoptotic cell death. In summary, our findings suggest that Nek5 promotes myogenic differentiation through up-regulation of caspase activity.
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Affiliation(s)
- Kouhei Shimizu
- Proteo-Science Center, Ehime University, Matsuyama 790-8577, Japan
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70
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Khanjyan MV, Yang J, Kayali R, Caldwell T, Bertoni C. A high-content, high-throughput siRNA screen identifies cyclin D2 as a potent regulator of muscle progenitor cell fusion and a target to enhance muscle regeneration. Hum Mol Genet 2013; 22:3283-95. [PMID: 23612904 DOI: 10.1093/hmg/ddt184] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Cell-mediated regenerative approaches using muscle progenitor cells hold promises for the treatment of many forms of muscle disorders. Their applicability in the clinic, however, is hindered by the low levels of regeneration obtained after transplantation and the large number of cells required to achieve an effect. To better understand the mechanisms that regulate the temporal switch of replicating muscle progenitor cells into terminally differentiated cells and to develop new strategies that could enhance muscle regeneration, we have developed and performed a high-throughput screening (HTS) capable of identifying genes that play active roles during myogenesis. Secondary and tertiary screens were used to confirm the effects of RNAi in vitro and in vivo and to select for candidate hits that significantly increase regeneration into skeletal muscles. Downregulation of cyclin D2 (CCND2) was shown to dramatically enhance myogenic differentiation of muscle progenitor cells and to induce a robust regeneration after cell transplantation into skeletal muscles of dystrophin-deficient mice. Protein interaction network and pathway analysis revealed that CCND2 directly interacts with the cyclin-dependent kinase Cdk4 to inhibit phosphorylation of the retinoblastoma protein (pRb), thus blocking the activation of the myogenic switch during fusion. These studies identify CCND2 as a new key regulator of terminal differentiation in muscle progenitor cells and open new possibilities for the treatment of many forms of muscle disorders characterized by impaired regeneration and loss of muscle mass.
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Affiliation(s)
- Michael V Khanjyan
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, 710 Westwood Plaza, Los Angeles, CA 90095, USA
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71
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Abstract
Adult skeletal muscle in mammals is a stable tissue under normal circumstances but has remarkable ability to repair after injury. Skeletal muscle regeneration is a highly orchestrated process involving the activation of various cellular and molecular responses. As skeletal muscle stem cells, satellite cells play an indispensible role in this process. The self-renewing proliferation of satellite cells not only maintains the stem cell population but also provides numerous myogenic cells, which proliferate, differentiate, fuse, and lead to new myofiber formation and reconstitution of a functional contractile apparatus. The complex behavior of satellite cells during skeletal muscle regeneration is tightly regulated through the dynamic interplay between intrinsic factors within satellite cells and extrinsic factors constituting the muscle stem cell niche/microenvironment. For the last half century, the advance of molecular biology, cell biology, and genetics has greatly improved our understanding of skeletal muscle biology. Here, we review some recent advances, with focuses on functions of satellite cells and their niche during the process of skeletal muscle regeneration.
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Affiliation(s)
- Hang Yin
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
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72
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Diao Y, Guo X, Li Y, Sun K, Lu L, Jiang L, Fu X, Zhu H, Sun H, Wang H, Wu Z. Pax3/7BP is a Pax7- and Pax3-binding protein that regulates the proliferation of muscle precursor cells by an epigenetic mechanism. Cell Stem Cell 2013; 11:231-41. [PMID: 22862948 DOI: 10.1016/j.stem.2012.05.022] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Revised: 04/16/2012] [Accepted: 05/11/2012] [Indexed: 11/26/2022]
Abstract
In mouse skeletal muscles, Pax7 uniquely marks muscle satellite cells and plays some important yet unknown functions at the perinatal stage. To elucidate its in vivo functions, we initiated a yeast two-hybrid screening to look for Pax7-interacting proteins and identified a previously uncharacterized Pax7- and Pax3-binding protein (Pax3/7BP). Pax3/7BP is a ubiquitously expressed nuclear protein, enriched in Pax7+ muscle precursor cells (MPCs), and serves as an indispensable adaptor for Pax7 to recruit the histone 3 lysine 4 (H3K4) methyltransferase (HMT) complex by bridging Pax7 and Wdr5. Knockdown of Pax3/7BP abolished the Pax3/7-associated H3K4 HMT activity and inhibited the proliferation of Pax7+ MPCs from young mice both in culture and in vivo. Id3 and Cdc20 were direct target genes of Pax7 and Pax3/7BP involved in the proliferation of Pax7+ MPCs. Collectively, our work establishes Pax3/7BP as an essential adaptor linking Pax3/7 with the H3K4 HMT to regulate the proliferation of MPCs.
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Affiliation(s)
- Yarui Diao
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong, China
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73
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Marchesi I, Nieddu V, Caracciolo V, Maioli M, Gaspa L, Giordano A, Bagella L. Activation and function of murine Cyclin T2A and Cyclin T2B during skeletal muscle differentiation. J Cell Biochem 2013; 114:728-34. [DOI: 10.1002/jcb.24414] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 09/28/2012] [Indexed: 12/14/2022]
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74
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Puri PL, Mercola M. BAF60 A, B, and Cs of muscle determination and renewal. Genes Dev 2012; 26:2673-83. [PMID: 23222103 DOI: 10.1101/gad.207415.112] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Developmental biologists have defined many of the diffusible and transcription factors that control muscle differentiation, yet we still have only rudimentary knowledge of the mechanisms that dictate whether a myogenic progenitor cell forms muscle versus alternate lineages, including those that can be pathological in a state of disease or degeneration. Clues about the molecular basis for lineage determination in muscle progenitors are only now emerging from studies of chromatin modifications that avail myogenic genes for transcription, together with analysis of the composition and activities of the chromatin-modifying complexes themselves. Here we review recent progress on muscle determination and explore a unifying theme that environmental cues from the stem or progenitor niche control the selection of specific subunit variants of the switch/sucrose nonfermentable (SWI/SNF) chromatin-modifying complex, creating a combinatorial code that dictates whether cells adopt myogenic versus nonmyogenic cell fates. A key component of the code appears to be the mutually exclusive usage of the a, b, and c variants of the 60-kD structural subunit BAF60 (BRG1/BRM-associated factor 60), of which BAF60c is essential to activate both skeletal and cardiac muscle programs. Since chromatin remodeling governs myogenic fate, the combinatorial assembly of the SWI/SNF complex might be targeted to develop drugs aimed at the therapeutic reduction of compensatory fibrosis and fatty deposition in chronic muscular disorders.
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Affiliation(s)
- Pier Lorenzo Puri
- Muscle Development and Regeneration Program, Sanford-Burnham Medical Research Institute, La Jolla, California 92037, USA.
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75
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Ling BMT, Gopinadhan S, Kok WK, Shankar SR, Gopal P, Bharathy N, Wang Y, Taneja R. G9a mediates Sharp-1-dependent inhibition of skeletal muscle differentiation. Mol Biol Cell 2012; 23:4778-85. [PMID: 23087213 PMCID: PMC3521685 DOI: 10.1091/mbc.e12-04-0311] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Sharp-1, a basic helix-loop-helix transcription factor, is a potent repressor of skeletal muscle differentiation and is dysregulated in muscle pathologies. However, the mechanisms by which it inhibits myogenesis are not fully understood. Here we show that G9a, a lysine methyltransferase, is involved in Sharp-1-mediated inhibition of muscle differentiation. We demonstrate that G9a directly interacts with Sharp-1 and enhances its ability to transcriptionally repress the myogenin promoter. Concomitant with a differentiation block, G9a-dependent histone H3 lysine 9 dimethylation (H3K9me2) and MyoD methylation are apparent upon Sharp-1 overexpression in muscle cells. RNA interference-mediated reduction of G9a or pharmacological inhibition of its activity erases these repressive marks and rescues the differentiation defect imposed by Sharp-1. Our findings provide new insights into Sharp-1-dependent regulation of myogenesis and identify epigenetic mechanisms that could be targeted in myopathies characterized by elevated Sharp-1 levels.
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Affiliation(s)
- Belinda Mei Tze Ling
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597
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76
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Marchesi I, Fiorentino FP, Rizzolio F, Giordano A, Bagella L. The ablation of EZH2 uncovers its crucial role in rhabdomyosarcoma formation. Cell Cycle 2012; 11:3828-36. [PMID: 22983009 DOI: 10.4161/cc.22025] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Rhabdomyosarcoma (RMS) is a pediatric tumor that arises from muscle precursor cells. RMS cells express several markers of early myogenic differentiation, but they fail to complete both differentiation program and cell cycle arrest, resulting in uncontrolled proliferation and incomplete myogenesis. Previous studies showed that EZH2, which is involved in both differentiation and cancer progression, is overexpressed in RMS, but a functional binding between its expression and its functional role in tumor formation or progression has not yet been demonstrated. We hypothesized that EZH2 is a key regulator of muscular differentiation program in RMS cells. In this study, we demonstrated that EZH2 directly binds muscle specific genes in RD cells. Silencing of EZH2 promotes the recruitment of a multiprotein complex at muscle-specific promoters, their transcriptional activation and protein expression. Moreover, we demonstrated that EZH2 is directly involved in transcriptional repression of MyoD, the main factor promoting myogenesis. EZH2 ablation induces MyoD activation the recovery of its binding on muscle-specific genes.
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Affiliation(s)
- Irene Marchesi
- Department of Biomedical Sciences, Division of Biochemistry and National Institute of Biostructures and Biosystems, University of Sassari, Sassari, Italy
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77
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Abstract
The transcription factor MyoD is a master regulator of skeletal muscle differentiation. The finding that G9a, an enzyme principally involved in histone H3 lysine 9 di-methylation (H3K9me2), methylates MyoD, identifies previously unappreciated mechanisms by which chromatin modifiers regulate the transcriptional activity of non-histone substrates to control cellular differentiation programs.
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Affiliation(s)
- Narendra Bharathy
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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78
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Busanello A, Battistelli C, Carbone M, Mostocotto C, Maione R. MyoD regulates p57kip2 expression by interacting with a distant cis-element and modifying a higher order chromatin structure. Nucleic Acids Res 2012; 40:8266-75. [PMID: 22740650 PMCID: PMC3458561 DOI: 10.1093/nar/gks619] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The bHLH transcription factor MyoD, the prototypical master regulator of differentiation, directs a complex program of gene expression during skeletal myogenesis. The up-regulation of the cdk inhibitor p57kip2 plays a critical role in coordinating differentiation and growth arrest during muscle development, as well as in other tissues. p57kip2 displays a highly specific expression pattern and is subject to a complex epigenetic control driving the imprinting of the paternal allele. However, the regulatory mechanisms governing its expression during development are still poorly understood. We have identified an unexpected mechanism by which MyoD regulates p57kip2 transcription in differentiating muscle cells. We show that the induction of p57kip2 requires MyoD binding to a long-distance element located within the imprinting control region KvDMR1 and the consequent release of a chromatin loop involving p57kip2 promoter. We also show that differentiation-dependent regulation of p57kip2, while involving a region implicated in the imprinting process, is distinct and hierarchically subordinated to the imprinting control. These findings highlight a novel mechanism, involving the modification of higher order chromatin structures, by which MyoD regulates gene expression. Our results also suggest that chromatin folding mediated by KvDMR1 could account for the highly restricted expression of p57kip2 during development and, possibly, for its aberrant silencing in some pathologies.
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Affiliation(s)
- Anna Busanello
- Istituto Pasteur-Fondazione Cenci Bolognetti, Dipartimento di Biotecnologie Cellulari ed Ematologia, Sezione di Genetica Molecolare, Università di Roma La Sapienza, Viale Regina Elena 324, Roma 00161, Italy
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79
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Fortini P, Ferretti C, Pascucci B, Narciso L, Pajalunga D, Puggioni EMR, Castino R, Isidoro C, Crescenzi M, Dogliotti E. DNA damage response by single-strand breaks in terminally differentiated muscle cells and the control of muscle integrity. Cell Death Differ 2012; 19:1741-9. [PMID: 22705848 DOI: 10.1038/cdd.2012.53] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
DNA single-strand breaks (SSB) formation coordinates the myogenic program, and defects in SSB repair in post-mitotic cells have been associated with human diseases. However, the DNA damage response by SSB in terminally differentiated cells has not been explored yet. Here we show that mouse post-mitotic muscle cells accumulate SSB after alkylation damage, but they are extraordinarily resistant to the killing effects of a variety of SSB-inducers. We demonstrate that, upon SSB induction, phosphorylation of H2AX occurs in myotubes and is largely ataxia telangiectasia mutated (ATM)-dependent. However, the DNA damage signaling cascade downstream of ATM is defective as shown by lack of p53 increase and phosphorylation at serine 18 (human serine 15). The stabilization of p53 by nutlin-3 was ineffective in activating the cell death pathway, indicating that the resistance to SSB inducers is due to defective p53 downstream signaling. The induction of specific types of damage is required to activate the cell death program in myotubes. Besides the topoisomerase inhibitor doxorubicin known for its cardiotoxicity, we show that the mitochondria-specific inhibitor menadione is able to activate p53 and to kill effectively myotubes. Cell killing is p53-dependent as demonstrated by full protection of myotubes lacking p53, but there is a restriction of p53-activated genes. This new information may have important therapeutic implications in the prevention of muscle cell toxicity.
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Affiliation(s)
- P Fortini
- Department of Environment and Primary Prevention, Istituto Superiore di Sanità, Rome, Italy
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80
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Wong CH, Mak GWY, Li MS, Tsui SKW. The LIM-only protein FHL2 regulates interleukin-6 expression through p38 MAPK mediated NF-κB pathway in muscle cells. Cytokine 2012; 59:286-93. [PMID: 22633286 DOI: 10.1016/j.cyto.2012.04.044] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 03/23/2012] [Accepted: 04/22/2012] [Indexed: 01/09/2023]
Abstract
Interleukin 6 (IL-6) is pleiotropic cytokine playing an important role in inflammatory response. Other than classical immune tissues, IL-6 is also produced in muscle cells under specific conditions. Four-and-a-half LIM-only protein 2 (FHL2) is preferentially expressed in skeletal and cardiac muscle cells compared to other tissues indicating it has an important role in skeletal muscle and cardiovascular system. In this report, the regulation of IL-6 by FHL2 in muscle cells was investigated. We demonstrated that FHL2 overexpression increased IL-6 mRNA level and its protein secretion in skeletal myoblasts. In contrast, the IL-6 secretion was significantly decreased after FHL2-knockdown by siRNA in response to TNFα stimulation. We further showed that FHL2-mediated induction of IL-6 was regulated by the activation of IL-6 promoter through stimulating NF-κB and p38 MAPK signaling pathway. Our results further illustrated the molecular mechanisms of IL-6 production, which provides new insights in the roles of FHL2 in post-injury inflammation or cytoprotection of muscle cells.
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Affiliation(s)
- Chi-Hang Wong
- Department of Clinical Oncology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong Special Administrative Region, China
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81
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Interplay between two myogenesis-related proteins: TBP-interacting protein 120B and MyoD. Gene 2012; 504:213-9. [PMID: 22613845 DOI: 10.1016/j.gene.2012.05.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 05/09/2012] [Accepted: 05/11/2012] [Indexed: 11/23/2022]
Abstract
Gene expression in myogenesis is governed by multiple myogenic factors including MyoD. Previously, we demonstrated that TBP-interacting protein 120B (TIP120B) promotes in vitro myogenesis through its anti-ubiquitination ability. In this study, we investigated interplay between MyoD and TIP120B. Mouse C2C12 cells subjected to myotube differentiation contained increased amounts of TIP120B and MyoD. Dexamethasone, which inhibits myogenic signaling, decreased the amounts of those proteins. Mouse and human TIP120B promoters, which carry multiple E-box motifs, were potentiated by MyoD. In the human TIP120B, a proximal E-box binds to MyoD in vitro and exhibits MyoD-dependent transcription activation function. Expression of the endogenous TIP120B gene was correlated with the level of MyoD in different types of muscle-related cells. Furthermore, MyoD binds specifically to a proximal E-box-carrying promoter region in chromatin. Proteasome-sensitive MyoD was increased and decreased by overexpression and knockdown of TIP120B, respectively. Moreover, stability of MyoD was increased by TIP120B. The results suggest that MyoD and TIP120B potentiate each other at gene expression and post-translation levels, respectively, which may promote myogenesis cooperatively.
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82
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Saccone V, Puri PL. Epigenetic regulation of skeletal myogenesis. Organogenesis 2012; 6:48-53. [PMID: 20592865 DOI: 10.4161/org.6.1.11293] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2010] [Revised: 01/24/2010] [Accepted: 01/25/2010] [Indexed: 12/31/2022] Open
Abstract
During embryogenesis a timely and coordinated expression of different subsets of genes drives the formation of skeletal muscles in response to developmental cues. In this review, we will summarize the most recent advances on the "epigenetic network" that promotes the transcription of selective groups of genes in muscle progenitors, through the concerted action of chromatin-associated complexes that modify histone tails and microRNAs (miRNAs). These epigenetic players cooperate to establish focal domains of euchromatin, which facilitates gene transcription, and large portions of heterochromatin, which precludes inappropriate gene expression. We also discuss the analogies and differences in the transcriptional and the epigenetic networks driving developmental and adult myogenesis. The elucidation of the epigenetic basis controlling skeletal myogenesis during development and adult life will facilitate experimental strategies toward generating muscle stem cells, either by reprogramming embryonic stem cells or by inducing pluripotency in adult skeletal muscles. During embryogenesis a timely and coordinated expression of different subsets of genes drives the formation of skeletal muscles in response to developmental cues. In this review, we will summarize the most recent advances on the "epigenetic network" that promotes the transcription of selective groups of genes in muscle progenitors, through the concerted action of chromatin-associated complexes that modify histone tails and microRNAs (miRNAs). These epigenetic players cooperate to establish focal domains of euchromatin, which facilitates gene transcription, and large portions of heterochromatin, which precludes inappropriate gene expression. We also discuss the analogies and differences in the transcriptional and the epigenetic networks driving developmental and adult myogenesis. The elucidation of the epigenetic basis controlling skeletal myogenesis during development and adult life will facilitate experimental strategies toward generating muscle stem cells, either by reprogramming embryonic stem cells or by inducing pluripotency in adult skeletal muscles.
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Affiliation(s)
- Valentina Saccone
- Istituto Dulbecco Telethon, IR CCS Santa Lucia Foundation and European Brain Research Institute, Rome, Italy
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83
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Srivastava S, Mishra RK, Dhawan J. Regulation of cellular chromatin state: insights from quiescence and differentiation. Organogenesis 2012; 6:37-47. [PMID: 20592864 DOI: 10.4161/org.6.1.11337] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2009] [Revised: 01/19/2010] [Accepted: 01/29/2010] [Indexed: 11/19/2022] Open
Abstract
The identity and functionality of eukaryotic cells is defined not just by their genomic sequence which remains constant between cell types, but by their gene expression profiles governed by epigenetic mechanisms. Epigenetic controls maintain and change the chromatin state throughout development, as exemplified by the setting up of cellular memory for the regulation and maintenance of homeotic genes in proliferating progenitors during embryonic development. Higher order chromatin structure in reversibly arrested adult stem cells also involves epigenetic regulation and in this review we highlight common trends governing chromatin states, focusing on quiescence and differentiation during myogenesis. Together, these diverse developmental modules reveal the dynamic nature of chromatin regulation providing fresh insights into the role of epigenetic mechanisms in potentiating development and differentiation.
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Affiliation(s)
- Surabhi Srivastava
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Hyderabad, India.
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84
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Abstract
Caveolins are scaffolding proteins that play a pivotal role in numerous processes, including caveolae biogenesis, vesicular transport, cholesterol homeostasis and regulation of signal transduction. There are three different isoforms (Cav-1, -2 and -3) that form homo- and hetero-aggregates at the plasma membrane and modulate the activity of a number of intracellular binding proteins. Cav-1 and Cav-3, in particular, are respectively expressed in the reserve elements (e.g. satellite cells) and in mature myofibres of skeletal muscle and their expression interplay characterizes the switch from muscle precursors to differentiated elements. Recent findings have shown that caveolins are also expressed in rhabdomyosarcoma, a group of heterogeneous childhood soft-tissue sarcomas in which the cancer cells seem to derive from progenitors that resemble myogenic cells. In this review, we will focus on the role of caveolins in rhabdomyosarcomas and on their potential use as markers of the degree of differentiation in these paediatric tumours. Given that the function of Cav-1 as tumour conditional gene in cancer has been well-established, we will also discuss the relationship between Cav-1 and the progression of rhabdomyosarcoma.
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Affiliation(s)
- Stefania Rossi
- Department of Biomedical Sciences and Biotechnologies, Interuniversity Institute of Myology (IIM), University of Brescia, Brescia, Italy Department of Pathology, University of Brescia, Brescia, Italy
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85
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Xiao F, Wang H, Fu X, Li Y, Wu Z. TRAF6 promotes myogenic differentiation via the TAK1/p38 mitogen-activated protein kinase and Akt pathways. PLoS One 2012; 7:e34081. [PMID: 22496778 PMCID: PMC3319550 DOI: 10.1371/journal.pone.0034081] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Accepted: 02/21/2012] [Indexed: 12/31/2022] Open
Abstract
p38 mitogen-activated protein kinase (MAPK) is an essential kinase involved in myogenic differentiation. Although many substrates of p38 MAPK have been identified, little is known about its upstream activators during myogenic differentiation. TRAF6 is known to function in cytokine signaling during inflammatory responses. However, not much is known about its role in myogenic differentiation and muscle regeneration. We showed here that TRAF6 and its intrinsic ubiquitin E3 ligase activity are required for myogenic differentiation. In mouse myoblasts, knockdown of TRAF6 compromised the p38 MAPK and Akt pathways, while deliberate activation of either pathway rescued the differentiation defect caused by TRAF6 knockdown. TAK1 acted as a key signal transducer downstream of TRAF6 in myogenic differentiation. In vivo, knockdown of TRAF6 in mouse muscles compromised the injury-induced muscle regeneration without impairing macrophage infiltration and myoblast proliferation. Collectively, we demonstrated that TRAF6 promotes myogenic differentiation and muscle regeneration via the TAK1/p38 MAPK and Akt pathways.
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Affiliation(s)
| | | | | | | | - Zhenguo Wu
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong, China
- * E-mail:
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86
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Forcales SV, Albini S, Giordani L, Malecova B, Cignolo L, Chernov A, Coutinho P, Saccone V, Consalvi S, Williams R, Wang K, Wu Z, Baranovskaya S, Miller A, Dilworth FJ, Puri PL. Signal-dependent incorporation of MyoD-BAF60c into Brg1-based SWI/SNF chromatin-remodelling complex. EMBO J 2011; 31:301-16. [PMID: 22068056 DOI: 10.1038/emboj.2011.391] [Citation(s) in RCA: 157] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Accepted: 10/02/2011] [Indexed: 12/13/2022] Open
Abstract
Tissue-specific transcriptional activators initiate differentiation towards specialized cell types by inducing chromatin modifications permissive for transcription at target loci, through the recruitment of SWItch/Sucrose NonFermentable (SWI/SNF) chromatin-remodelling complex. However, the molecular mechanism that regulates SWI/SNF nuclear distribution in response to differentiation signals is unknown. We show that the muscle determination factor MyoD and the SWI/SNF subunit BAF60c interact on the regulatory elements of MyoD-target genes in myoblasts, prior to activation of transcription. BAF60c facilitates MyoD binding to target genes and marks the chromatin for signal-dependent recruitment of the SWI/SNF core to muscle genes. BAF60c phosphorylation on a conserved threonine by differentiation-activated p38α kinase is the signal that promotes incorporation of MyoD-BAF60c into a Brg1-based SWI/SNF complex, which remodels the chromatin and activates transcription of MyoD-target genes. Our data support an unprecedented two-step model by which pre-assembled BAF60c-MyoD complex directs recruitment of SWI/SNF to muscle loci in response to differentiation cues.
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Affiliation(s)
- Sonia V Forcales
- Muscle Development and Regeneration Program, Sanford-Burnham Institute for Medical Research, La Jolla, CA, USA
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87
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Yang W, Itoh F, Ohya H, Kishimoto F, Tanaka A, Nakano N, Itoh S, Kato M. Interference of E2-2-mediated effect in endothelial cells by FAM96B through its limited expression of E2-2. Cancer Sci 2011; 102:1808-14. [DOI: 10.1111/j.1349-7006.2011.02022.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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88
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Simonatto M, Giordani L, Marullo F, Minetti GC, Puri PL, Latella L. Coordination of cell cycle, DNA repair and muscle gene expression in myoblasts exposed to genotoxic stress. Cell Cycle 2011; 10:2355-63. [PMID: 21685725 DOI: 10.4161/cc.10.14.15948] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Upon exposure to genotoxic stress, skeletal muscle progenitors coordinate DNA repair and the activation of the differentiation program through the DNA damage-activated differentiation checkpoint, which holds the transcription of differentiation genes while the DNA is repaired. A conceptual hurdle intrinsic to this process relates to the coordination of DNA repair and muscle-specific gene transcription within specific cell cycle boundaries (cell cycle checkpoints) activated by different types of genotoxins. Here, we show that, in proliferating myoblasts, the inhibition of muscle gene transcription occurs by either a G 1- or G 2-specific differentiation checkpoint. In response to genotoxins that induce G 1 arrest, MyoD binds target genes but is functionally inactivated by a c-Abl-dependent phosphorylation. In contrast, DNA damage-activated G 2 checkpoint relies on the inability of MyoD to bind the chromatin at the G 2 phase of the cell cycle. These results indicate an intimate relationship between DNA damage-activated cell cycle checkpoints and the control of tissue-specific gene expression to allow DNA repair in myoblasts prior to the activation of the differentiation program.
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Affiliation(s)
- Marta Simonatto
- Istituto Dulbecco Telethon, IRCCS Fondazione Santa Lucia and European Brain Research Institute, Rome, Italy
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89
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Doherty JT, Lenhart KC, Cameron MV, Mack CP, Conlon FL, Taylor JM. Skeletal muscle differentiation and fusion are regulated by the BAR-containing Rho-GTPase-activating protein (Rho-GAP), GRAF1. J Biol Chem 2011; 286:25903-21. [PMID: 21622574 DOI: 10.1074/jbc.m111.243030] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Although RhoA activity is necessary for promoting myogenic mesenchymal stem cell fates, recent studies in cultured cells suggest that down-regulation of RhoA activity in specified myoblasts is required for subsequent differentiation and myotube formation. However, whether this phenomenon occurs in vivo and which Rho modifiers control these later events remain unclear. We found that expression of the Rho-GTPase-activating protein, GRAF1, was transiently up-regulated during myogenesis, and studies in C2C12 cells revealed that GRAF1 is necessary and sufficient for mediating RhoA down-regulation and inducing muscle differentiation. Moreover, forced expression of GRAF1 in pre-differentiated myoblasts drives robust muscle fusion by a process that requires GTPase-activating protein-dependent actin remodeling and BAR-dependent membrane binding or sculpting. Moreover, morpholino-based knockdown studies in Xenopus laevis determined that GRAF1 expression is critical for muscle development. GRAF1-depleted embryos exhibited elevated RhoA activity and defective myofibrillogenesis that resulted in progressive muscle degeneration, defective motility, and embryonic lethality. Our results are the first to identify a GTPase-activating protein that regulates muscle maturation and to highlight the functional importance of BAR domains in myotube formation.
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90
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Hamuro J, Hishida Y, Higuchi O, Yamanashi Y. The transcription factor Sp1 plays a crucial role in dok-7 gene expression. Biochem Biophys Res Commun 2011; 408:293-9. [DOI: 10.1016/j.bbrc.2011.04.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Accepted: 04/05/2011] [Indexed: 11/27/2022]
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91
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Sousa-Victor P, Muñoz-Cánoves P, Perdiguero E. Regulation of skeletal muscle stem cells through epigenetic mechanisms. Toxicol Mech Methods 2011; 21:334-42. [DOI: 10.3109/15376516.2011.557873] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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92
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Lee MH, Jothi M, Gudkov AV, Mal AK. Histone methyltransferase KMT1A restrains entry of alveolar rhabdomyosarcoma cells into a myogenic differentiated state. Cancer Res 2011; 71:3921-31. [PMID: 21493592 DOI: 10.1158/0008-5472.can-10-3358] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Alveolar rhabdomyosarcoma (ARMS) is an aggressive pediatric muscle cancer, which arrested during the process of skeletal muscle differentiation. In muscle myoblast cells, ectopic expression of the histone H3 lysine 9 (H3K9) methytransferase KMT1A blocks differentiation by repressing a myogenic gene expression program. In this study, we tested the hypothesis that activation of a KMT1A-mediated program of transcriptional repression prevents ARMS cells from differentiating. We investigated whether KMT1A represses the expression of differentiation-associated genes in ARMS cells, thereby blocking muscle differentiation. Our results show that expression of KMT1A is induced in human ARMS cancer cell lines when cultured under differentiation-permissible conditions. shRNA-mediated knockdown of KMT1A decreased anchorage dependent and independent cell proliferation and tumor xenograft growth, increased expression of differentiation-associated genes, and promoted the appearance of a terminally differentiated-like phenotype. Finally, shRNA-directed KMT1A knockdown restored the impaired transcriptional activity of the myogenic regulator MyoD. Together, our results suggested that high levels of KMT1A in ARMS cells under differentiation conditions impairs MyoD function, thereby arresting myogenic differentiation in these tumor cells. Thus, targeting KMT1A may be a novel strategy for the treatment of this disease.
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Affiliation(s)
- Min-Hyung Lee
- Department of Cell Stress Biology, Roswell Park Cancer Institute, Buffalo, New York 14263, USA
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93
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Jo C, Cho SJ, Jo SA. Mitogen-activated protein kinase kinase 1 (MEK1) stabilizes MyoD through direct phosphorylation at tyrosine 156 during myogenic differentiation. J Biol Chem 2011; 286:18903-13. [PMID: 21454680 DOI: 10.1074/jbc.m111.225128] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previously, we reported that mitogen-activated protein kinase kinase 1 (MEK1) activated in the mid-stage of skeletal muscle differentiation promotes myogenic differentiation. To elucidate the molecular mechanism, we investigated an activity of MEK1 for MyoD. Activated MEK1 associates with MyoD in the nucleus of differentiating myoblasts. In vitro kinase assay using active MEK1, a (32)P-labeled protein band corresponding to GST-MyoD was observed but not to mutant GST-MyoD-Y156F. Tyrosine phosphorylation of endogenous MyoD was detected with a specific anti-pMyoD-Y156 antibody; however, this response was blocked by PD184352, a MEK-specific inhibitor. These results indicate that activated MEK1 phosphorylates the MyoD-Y156 residue directly. Interestingly, the protein level of mutant MyoD-Y156F decreased compared with that of wild type but was recovered in the presence of lactacystin, a proteasome inhibitor. The protein level of MyoD-Y156E, which mimics phosphorylation at Tyr-156, was above that of wild type, indicating that the phosphorylation protects MyoD from the ubiquitin proteasome-mediated degradation. In addition, the low protein level of MyoD-Y156F was recovered over that of wild type by an additional mutation at Leu-164, a critical binding residue of MAFbx/AT-1, a Skp, Cullin, F-box (SCF) E3-ubiquitin ligase. The amount of MyoD co-precipitated with MAFbx/AT-1 also was reduced in the presence of active MEK1. Thus, these results suggested that the phosphorylation probably interrupts the binding of MAFbx/AT-1 to MyoD and thereby increases its stability. Collectively, our results suggest that MEK1 activated in differentiating myoblasts stimulates muscle differentiation by phosphorylating MyoD-Y156, which results in MyoD stabilization.
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Affiliation(s)
- Chulman Jo
- Division of Brain Disease, Center for Biomedical Science, National Institutes of Health, Korea Center for Disease Control and Prevention, 187 Osongsaengmyeong2-ro, Gangoe-myeon, Cheongwon-gun, Chungcheongbuk-do 363-951, South Korea
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94
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Abstract
Myogenesis has been a leading model for elucidating the molecular mechanisms that underlie tissue differentiation and development since the discovery of MyoD. During myogenesis, the fate of myogenic precursor cells is first determined by Pax3/Pax7. This is followed by regulation of the myogenic differentiation program by muscle regulatory factors (Myf5, MyoD, Myog, and Mrf4) to form muscle tissues. Recent studies have uncovered a detailed myogenic program that involves the RP58 (Zfp238)-dependent regulatory network, which is critical for repressing the expression of inhibitor of DNA binding (Id) proteins. These novel findings contribute to a comprehensive understanding of the muscle differentiation transcriptional program.
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95
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Consalvi S, Saccone V, Giordani L, Minetti G, Mozzetta C, Puri PL. Histone deacetylase inhibitors in the treatment of muscular dystrophies: epigenetic drugs for genetic diseases. Mol Med 2011; 17:457-65. [PMID: 21308150 DOI: 10.2119/molmed.2011.00049] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Accepted: 02/07/2011] [Indexed: 12/21/2022] Open
Abstract
Histone deacetylases inhibitors (HDACi) include a growing number of drugs that share the ability to inhibit the enzymatic activity of some or all the HDACs. Experimental and preclinical evidence indicates that these epigenetic drugs not only can be effective in the treatment of malignancies, inflammatory diseases and degenerative disorders, but also in the treatment of genetic diseases, such as muscular dystrophies. The ability of HDACi to counter the progression of muscular dystrophies points to HDACs as a crucial link between specific genetic mutations and downstream determinants of disease progression. It also suggests the contribution of epigenetic events to the pathogenesis of muscular dystrophies. Here we describe the experimental evidence supporting the key role of HDACs in the control of the transcriptional networks underlying the potential of dystrophic muscles either to activate compensatory regeneration or to undergo fibroadipogenic degeneration. Studies performed in mouse models of Duchenne muscular dystrophy (DMD) indicate that dystrophin deficiency leads to deregulated HDAC activity, which perturbs downstream networks and can be restored directly, by HDAC blockade, or indirectly, by reexpression of dystrophin. This evidence supports the current view that HDACi are emerging candidate drugs for pharmacological interventions in muscular dystrophies, and reveals unexpected common beneficial outcomes of pharmacological treatment or gene therapy.
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Affiliation(s)
- Silvia Consalvi
- Dulbecco Telethon Institute (DTI), IRCCS Fondazione Santa Lucia, and European Brain Research Institute, Rome, Italy
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96
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Delgado-Olguín P, Brand-Arzamendi K, Scott IC, Jungblut B, Stainier DY, Bruneau BG, Recillas-Targa F. CTCF promotes muscle differentiation by modulating the activity of myogenic regulatory factors. J Biol Chem 2011; 286:12483-94. [PMID: 21288905 DOI: 10.1074/jbc.m110.164574] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
CTCF nuclear factor regulates many aspects of gene expression, largely as a transcriptional repressor or via insulator function. Its roles in cellular differentiation are not clear. Here we show an unexpected role for CTCF in myogenesis. Ctcf is expressed in myogenic structures during mouse and zebrafish development. Gain- and loss-of-function approaches in C2C12 cells revealed CTCF as a modulator of myogenesis by regulating muscle-specific gene expression. We addressed the functional connection between CTCF and myogenic regulatory factors (MRFs). CTCF enhances the myogenic potential of MyoD and myogenin and establishes direct interactions with MyoD, indicating that CTCF regulates MRF-mediated muscle differentiation. Indeed, CTCF modulates functional interactions between MyoD and myogenin in co-activation of muscle-specific gene expression and facilitates MyoD recruitment to a muscle-specific promoter. Finally, ctcf loss-of-function experiments in zebrafish embryos revealed a critical role of CTCF in myogenic development and linked CTCF to broader aspects of development via regulation of Wnt signaling. We conclude that CTCF modulates MRF functional interactions in the orchestration of myogenesis.
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Affiliation(s)
- Paul Delgado-Olguín
- Gladstone Institute of Cardiovascular Disease, Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA 94158, USA
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97
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Expression of Gαz in C2C12 cells restrains myogenic differentiation. Cell Signal 2011; 23:389-97. [DOI: 10.1016/j.cellsig.2010.10.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Revised: 09/16/2010] [Accepted: 10/01/2010] [Indexed: 10/19/2022]
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98
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An evolutionarily acquired genotoxic response discriminates MyoD from Myf5, and differentially regulates hypaxial and epaxial myogenesis. EMBO Rep 2011; 12:164-71. [PMID: 21212806 DOI: 10.1038/embor.2010.195] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Revised: 11/05/2010] [Accepted: 11/15/2010] [Indexed: 11/08/2022] Open
Abstract
Despite having distinct expression patterns and phenotypes in mutant mice, the myogenic regulatory factors Myf5 and MyoD have been considered to be functionally equivalent. Here, we report that these factors have a different response to DNA damage, due to the presence in MyoD and absence in Myf5 of a consensus site for Abl-mediated tyrosine phosphorylation that inhibits MyoD activity in response to DNA damage. Genotoxins failed to repress skeletal myogenesis in MyoD-null embryos; reintroduction of wild-type MyoD, but not mutant Abl phosphorylation-resistant MyoD, restored the DNA-damage-dependent inhibition of muscle differentiation. Conversely, introduction of the Abl-responsive phosphorylation motif converts Myf5 into a DNA-damage-sensitive transcription factor. Gene-dosage-dependent reduction of Abl kinase activity in MyoD-expressing cells attenuated the DNA-damage-dependent inhibition of myogenesis. The presence of a DNA-damage-responsive phosphorylation motif in vertebrate, but not in invertebrate MyoD suggests an evolved response to environmental stress, originated from basic helix-loop-helix gene duplication in vertebrate myogenesis.
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99
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Saab R, Spunt SL, Skapek SX. Myogenesis and rhabdomyosarcoma the Jekyll and Hyde of skeletal muscle. Curr Top Dev Biol 2011; 94:197-234. [PMID: 21295688 DOI: 10.1016/b978-0-12-380916-2.00007-3] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Rhabdomyosarcoma, a neoplasm composed of skeletal myoblast-like cells, represents the most common soft tissue sarcoma in children. The application of intensive chemotherapeutics and refined surgical and radiation therapy approaches have improved survival for children with localized disease over the past 3 decades; however, these approaches have not improved the dismal outcome for children with metastatic and recurrent rhabdomyosarcoma. Elegant studies have defined the molecular mechanisms driving skeletal muscle lineage commitment and differentiation, and the machinery that couples differentiation with irreversible cell proliferation arrest. Further, detailed molecular analyses indicate that rhabdomyosarcoma cells have lost the capacity to fully differentiate when challenged to do so in experimental models. We review the intersection of normal skeletal muscle developmental biology and the molecular genetic defects in rhabdomyosarcoma with the underlying premise that understanding how the differentiation process has gone awry will lead to new treatment strategies aimed at promoting myogenic differentiation and concomitant cell cycle arrest.
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Affiliation(s)
- Raya Saab
- Children's Cancer Center of Lebanon, Department of Pediatrics, American University of Beirut, Beirut, Lebanon
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100
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Eilon T, Barash I. Forced activation of Stat5 subjects mammary epithelial cells to DNA damage and preferential induction of the cellular response mechanism during proliferation. J Cell Physiol 2010; 226:616-26. [DOI: 10.1002/jcp.22381] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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