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Wood WM, Etemad S, Yamamoto M, Goldhamer DJ. MyoD-expressing progenitors are essential for skeletal myogenesis and satellite cell development. Dev Biol 2013; 384:114-27. [PMID: 24055173 DOI: 10.1016/j.ydbio.2013.09.012] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2013] [Revised: 09/06/2013] [Accepted: 09/07/2013] [Indexed: 01/22/2023]
Abstract
Skeletal myogenesis in the embryo is regulated by the coordinated expression of the MyoD family of muscle regulatory factors (MRFs). MyoD and Myf-5, which are the primary muscle lineage-determining factors, function in a partially redundant manner to establish muscle progenitor cell identity. Previous diphtheria toxin (DTA)-mediated ablation studies showed that MyoD+ progenitors rescue myogenesis in embryos in which Myf-5-expressing cells were targeted for ablation, raising the possibility that the regulative behavior of distinct, MRF-expressing populations explains the functional compensatory activities of these MRFs. Using MyoD(iCre) mice, we show that DTA-mediated ablation of MyoD-expressing cells results in the cessation of myogenesis by embryonic day 12.5 (E12.5), as assayed by myosin heavy chain (MyHC) and Myogenin staining. Importantly, MyoD(iCre/+);R26(DTA/+) embryos exhibited a concomitant loss of Myf-5+ progenitors, indicating that the vast majority of Myf-5+ progenitors express MyoD, a conclusion consistent with immunofluorescence analysis of Myf-5 protein expression in MyoD(iCre) lineage-labeled embryos. Surprisingly, staining for the paired box transcription factor, Pax7, which functions genetically upstream of MyoD in the trunk and is a marker for fetal myoblasts and satellite cell progenitors, was also lost by E12.5. Specific ablation of differentiating skeletal muscle in ACTA1Cre;R26(DTA/+) embryos resulted in comparatively minor effects on MyoD+, Myf-5+ and Pax7+ progenitors, indicating that cell non-autonomous effects are unlikely to explain the rapid loss of myogenic progenitors in MyoD(iCre/+);R26(DTA/+) embryos. We conclude that the vast majority of myogenic cells transit through a MyoD+ state, and that MyoD+ progenitors are essential for myogenesis and stem cell development.
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Affiliation(s)
- William M Wood
- Department of Molecular and Cell Biology, University of Connecticut Stem Cell Institute, University of Connecticut, Storrs, CT, USA
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152
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Weimer K, Theobald J, Campbell KS, Esser KA, DiMario JX. Genome-wide expression analysis and EMX2 gene expression in embryonic myoblasts committed to diverse skeletal muscle fiber type fates. Dev Dyn 2013; 242:1001-20. [PMID: 23703830 PMCID: PMC3763492 DOI: 10.1002/dvdy.23988] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 04/24/2013] [Accepted: 05/07/2013] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND Primary skeletal muscle fibers form during embryonic development and are characterized as fast or slow fibers based on contractile protein gene expression. Different avian primary muscle fiber types arise from myoblast lineages committed to formation of diverse fiber types. To understand the basis of embryonic muscle fiber type diversity and the distinct myoblast lineages that generate this diversity, gene expression analyses were conducted on differentiated muscle fiber types and their respective myoblast precursor lineages. RESULTS Embryonic fast muscle fibers preferentially expressed 718 genes, and embryonic fast/slow muscle fibers differentially expressed 799 genes. Fast and fast/slow myoblast lineages displayed appreciable diversity in their gene expression profiles, indicating diversity of precursor myoblasts. Several genes, including the transcriptional regulator EMX2, were differentially expressed in both fast/slow myoblasts and muscle fibers vs. fast myoblasts and muscle fibers. EMX2 was localized to nuclei of fast/slow myoblasts and muscle fibers and was not detected in fast lineage cells. Furthermore, EMX2 overexpression and knockdown studies indicated that EMX2 is a positive transcriptional regulator of the slow myosin heavy chain 2 (MyHC2) gene promoter activity in fast/slow muscle fibers. CONCLUSIONS These results indicate the presence of distinct molecular signatures that characterize diverse embryonic myoblast lineages before differentiation.
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Affiliation(s)
- Kristina Weimer
- Rosalind Franklin University of Medicine and Science, School of Graduate and Postdoctoral Studies, Department of Cell Biology and Anatomy, 3333 Green Bay Road, North Chicago, IL 60064
| | - Jillian Theobald
- Rosalind Franklin University of Medicine and Science, School of Graduate and Postdoctoral Studies, Department of Cell Biology and Anatomy, 3333 Green Bay Road, North Chicago, IL 60064
| | - Kenneth S. Campbell
- Center for Muscle Biology, Department of Physiology, University of Kentucky, Lexington, KY 40536
| | - Karyn A. Esser
- Center for Muscle Biology, Department of Physiology, University of Kentucky, Lexington, KY 40536
| | - Joseph X. DiMario
- Rosalind Franklin University of Medicine and Science, School of Graduate and Postdoctoral Studies, Department of Cell Biology and Anatomy, 3333 Green Bay Road, North Chicago, IL 60064
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153
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Lee ASJ, Harris J, Bate M, Vijayraghavan K, Fisher L, Tajbakhsh S, Duxson M. Initiation of primary myogenesis in amniote limb muscles. Dev Dyn 2013; 242:1043-55. [PMID: 23765941 DOI: 10.1002/dvdy.23998] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2013] [Accepted: 05/21/2013] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Vertebrate muscles are defined and patterned at the stage of primary myotube formation, but there is no clear description of how these cells form in vivo. Of particular interest is whether primary myotubes are "seeded" by a unique myoblast population that differentiates as mononucleated myocytes, similar to the founder myoblasts of insects. RESULTS We analyzed the cell populations and processes leading to initiation of primary myogenesis in limb buds of rats and mice. Pax3(+ve) myogenic precursors migrate into the limb bud and initially consolidate into dorsal and ventral muscle masses in the absence of Pax7 expression. Approximately a day later, Pax7(+ve) cells appear in the central aspect of the limb base and subsequently throughout the limb muscle masses. Primary myogenesis is initiated within each muscle mass at a time when only Pax3, and not Pax7, protein can be detected. Primary myotubes form initially as elongate mononucleated myocytes, well before cleavage of the muscle masses has occurred. Multinucleate myotubes appear approximately a day later. A similar process is seen during initiation of chick limb primary myogenesis. CONCLUSIONS Primary myotubes of vertebrate limb muscles are initiated by mononucleated myocytes, that appear structurally analogous to the founder myoblasts of insects.
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Affiliation(s)
- Antonio S J Lee
- Department of Anatomy, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
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154
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Veldman MB, Zhao C, Gomez GA, Lindgren AG, Huang H, Yang H, Yao S, Martin BL, Kimelman D, Lin S. Transdifferentiation of fast skeletal muscle into functional endothelium in vivo by transcription factor Etv2. PLoS Biol 2013; 11:e1001590. [PMID: 23853546 PMCID: PMC3708712 DOI: 10.1371/journal.pbio.1001590] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 05/09/2013] [Indexed: 02/05/2023] Open
Abstract
Etv2, a master regulator of endothelial cell fate, can induce fast skeletal muscle cells to transdifferentiate into endothelial cells in the zebrafish embryo. Etsrp/Etv2 (Etv2) is an evolutionarily conserved master regulator of vascular development in vertebrates. Etv2 deficiency prevents the proper specification of the endothelial cell lineage, while its overexpression causes expansion of the endothelial cell lineage in the early embryo or in embryonic stem cells. We hypothesized that Etv2 alone is capable of transdifferentiating later somatic cells into endothelial cells. Using heat shock inducible Etv2 transgenic zebrafish, we demonstrate that Etv2 expression alone is sufficient to transdifferentiate fast skeletal muscle cells into functional blood vessels. Following heat treatment, fast skeletal muscle cells turn on vascular genes and repress muscle genes. Time-lapse imaging clearly shows that muscle cells turn on vascular gene expression, undergo dramatic morphological changes, and integrate into the existing vascular network. Lineage tracing and immunostaining confirm that fast skeletal muscle cells are the source of these newly generated vessels. Microangiography and observed blood flow demonstrated that this new vasculature is capable of supporting circulation. Using pharmacological, transgenic, and morpholino approaches, we further establish that the canonical Wnt pathway is important for induction of the transdifferentiation process, whereas the VEGF pathway provides a maturation signal for the endothelial fate. Additionally, overexpression of Etv2 in mammalian myoblast cells, but not in other cell types examined, induced expression of vascular genes. We have demonstrated in zebrafish that expression of Etv2 alone is sufficient to transdifferentiate fast skeletal muscle into functional endothelial cells in vivo. Given the evolutionarily conserved function of this transcription factor and the responsiveness of mammalian myoblasts to Etv2, it is likely that mammalian muscle cells will respond similarly. The endothelial cell is a specialized cell type that lines blood vessels. These cells are involved in normal cardiovascular function and become damaged in cardiovascular disease states such as atherosclerosis and stroke. We have discovered that developing muscle cells in the zebrafish embryo can be converted into endothelial cells by the expression of a transcription factor called Etv2. Etv2 normally functions during embryonic development to specify blood and blood vessels. When expressed in muscle cells, Etv2 induces the expression of genes that are normally expressed in endothelial cells; it also represses muscle gene expression. On expressing Etv2, muscle cells change shape and go on to form lumenized blood vessels that connect to the existing circulatory system and support blood flow. The Wnt and VEGF signaling pathways are required for this fate transformation. Our results suggest that muscle cells may be a viable source for the de novo generation of endothelial cells for use in transplantation therapies and they highlight signalling pathways that might be manipulated to improve the efficiency of this process in mammalian cells.
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Affiliation(s)
- Matthew B. Veldman
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, West China Medical School, Sichuan University, Chengdu, Sichuan, People's Republic of China
- Department of Molecular, Cell and Developmental Biology, University of California–Los Angeles, Los Angeles, California, United States of America
| | - Chengjian Zhao
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, West China Medical School, Sichuan University, Chengdu, Sichuan, People's Republic of China
- Department of Molecular, Cell and Developmental Biology, University of California–Los Angeles, Los Angeles, California, United States of America
| | - Gustavo A. Gomez
- Department of Molecular, Cell and Developmental Biology, University of California–Los Angeles, Los Angeles, California, United States of America
| | - Anne G. Lindgren
- Department of Molecular, Cell and Developmental Biology, University of California–Los Angeles, Los Angeles, California, United States of America
| | - Haigen Huang
- Department of Molecular, Cell and Developmental Biology, University of California–Los Angeles, Los Angeles, California, United States of America
| | - Hanshuo Yang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, West China Medical School, Sichuan University, Chengdu, Sichuan, People's Republic of China
- Department of Molecular, Cell and Developmental Biology, University of California–Los Angeles, Los Angeles, California, United States of America
| | - Shaohua Yao
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, West China Medical School, Sichuan University, Chengdu, Sichuan, People's Republic of China
- Department of Molecular, Cell and Developmental Biology, University of California–Los Angeles, Los Angeles, California, United States of America
| | - Benjamin L. Martin
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - David Kimelman
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Shuo Lin
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, West China Medical School, Sichuan University, Chengdu, Sichuan, People's Republic of China
- Department of Molecular, Cell and Developmental Biology, University of California–Los Angeles, Los Angeles, California, United States of America
- * E-mail:
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155
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Pistocchi A, Gaudenzi G, Foglia E, Monteverde S, Moreno-Fortuny A, Pianca A, Cossu G, Cotelli F, Messina G. Conserved and divergent functions of Nfix in skeletal muscle development during vertebrate evolution. Development 2013; 140:1528-36. [PMID: 23482488 DOI: 10.1242/dev.076315] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During mouse skeletal muscle development, the Nfix gene has a pivotal role in regulating fetal-specific transcription. Zebrafish and mice share related programs for muscle development, although zebrafish develops at a much faster rate. In fact, although mouse fetal muscle fibers form after 15 days of development, in fish secondary muscle fibers form by 48 hours post-fertilization in a process that until now has been poorly characterized mechanically. In this work, we studied the zebrafish ortholog Nfix (nfixa) and its role in the proper switch to the secondary myogenic wave. This allowed us to highlight evolutionarily conserved and divergent functions of Nfix. In fact, the knock down of nfixa in zebrafish blocks secondary myogenesis, as in mouse, but also alters primary slow muscle fiber formation. Moreover, whereas Nfix mutant mice are motile, nfixa knockdown zebrafish display impaired motility that probably depends upon disruption of the sarcoplasmic reticulum. We conclude that, during vertebrate evolution, the transcription factor Nfix lost some specific functions, probably as a consequence of the different environment in which teleosts and mammals develop.
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Affiliation(s)
- Anna Pistocchi
- Department of Biosciences, University of Milan, via Celoria 26, 20133 Milan, Italy
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156
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Sakai H, Sato T, Sakurai H, Yamamoto T, Hanaoka K, Montarras D, Sehara-Fujisawa A. Fetal skeletal muscle progenitors have regenerative capacity after intramuscular engraftment in dystrophin deficient mice. PLoS One 2013; 8:e63016. [PMID: 23671652 PMCID: PMC3650009 DOI: 10.1371/journal.pone.0063016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Accepted: 03/27/2013] [Indexed: 12/13/2022] Open
Abstract
Muscle satellite cells (SCs) are stem cells that reside in skeletal muscles and contribute to regeneration upon muscle injury. SCs arise from skeletal muscle progenitors expressing transcription factors Pax3 and/or Pax7 during embryogenesis in mice. However, it is unclear whether these fetal progenitors possess regenerative ability when transplanted in adult muscle. Here we address this question by investigating whether fetal skeletal muscle progenitors (FMPs) isolated from Pax3GFP/+ embryos have the capacity to regenerate muscle after engraftment into Dystrophin-deficient mice, a model of Duchenne muscular dystrophy. The capacity of FMPs to engraft and enter the myogenic program in regenerating muscle was compared with that of SCs derived from adult Pax3GFP/+ mice. Transplanted FMPs contributed to the reconstitution of damaged myofibers in Dystrophin-deficient mice. However, despite FMPs and SCs having similar myogenic ability in culture, the regenerative ability of FMPs was less than that of SCs in vivo. FMPs that had activated MyoD engrafted more efficiently to regenerate myofibers than MyoD-negative FMPs. Transcriptome and surface marker analyses of these cells suggest the importance of myogenic priming for the efficient myogenic engraftment. Our findings suggest the regenerative capability of FMPs in the context of muscle repair and cell therapy for degenerative muscle disease.
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MESH Headings
- Animals
- Cells, Cultured
- Dystrophin/deficiency
- Dystrophin/genetics
- Green Fluorescent Proteins/genetics
- Green Fluorescent Proteins/metabolism
- Immunohistochemistry
- Injections, Intramuscular
- Mice
- Mice, Knockout
- Mice, Transgenic
- Muscle, Skeletal/cytology
- Muscle, Skeletal/embryology
- Muscular Dystrophy, Animal/genetics
- Muscular Dystrophy, Animal/physiopathology
- Muscular Dystrophy, Animal/surgery
- Muscular Dystrophy, Duchenne/genetics
- Muscular Dystrophy, Duchenne/physiopathology
- Muscular Dystrophy, Duchenne/surgery
- MyoD Protein/genetics
- MyoD Protein/metabolism
- Myoblasts, Skeletal/metabolism
- Myoblasts, Skeletal/transplantation
- Myofibrils/genetics
- Myofibrils/physiology
- Myogenin/genetics
- Myogenin/metabolism
- PAX3 Transcription Factor
- Paired Box Transcription Factors/genetics
- Paired Box Transcription Factors/metabolism
- Regeneration/physiology
- Reverse Transcriptase Polymerase Chain Reaction
- Satellite Cells, Skeletal Muscle/transplantation
- Stem Cell Transplantation/methods
- Transcriptome
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Affiliation(s)
- Hiroshi Sakai
- Department of Growth Regulation, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan
| | - Takahiko Sato
- Department of Growth Regulation, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan
- * E-mail: (TS); (AS-F)
| | - Hidetoshi Sakurai
- Department of Clinical Application, Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan
| | - Takuya Yamamoto
- Department of Reprogramming Science, Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan
| | - Kazunori Hanaoka
- Laboratory of Molecular Embryology, Department of Bioscience, Kitasato University School of Science, Kanagawa, Japan
| | - Didier Montarras
- Molecular Genetics of Development, Institut Pasteur, Paris, France
| | - Atsuko Sehara-Fujisawa
- Department of Growth Regulation, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan
- * E-mail: (TS); (AS-F)
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157
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Biressi S, Bjornson CRR, Carlig PMM, Nishijo K, Keller C, Rando TA. Myf5 expression during fetal myogenesis defines the developmental progenitors of adult satellite cells. Dev Biol 2013; 379:195-207. [PMID: 23639729 DOI: 10.1016/j.ydbio.2013.04.021] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Revised: 03/21/2013] [Accepted: 04/09/2013] [Indexed: 01/06/2023]
Abstract
Myf5 is a member of the muscle-specific determination genes and plays a critical role in skeletal muscle development. Whereas the expression of Myf5 during embryonic and fetal myogenesis has been extensively studied, its expression in progenitors that will ultimately give rise to adult satellite cells, the stem cells responsible for muscle repair, is still largely unexplored. To investigate this aspect, we have generated a mouse strain carrying a CreER coding sequence in the Myf5 locus. In this strain, Tamoxifen-inducible Cre activity parallels endogenous Myf5 expression. Combining Myf5(CreER) and Cre reporter alleles, we were able to evaluate the contribution of cells expressing Myf5 at distinct developmental stages to the pool of satellite cells in adult hindlimb muscles. Although it was possible to trace back the origin of some rare satellite cells to a subpopulation of Myf5(+ve) progenitors in the limb buds at the late embryonic stage (∼E12), a significant number of satellite cells arise from cells which expressed Myf5 for the first time at the fetal stage (∼E15). These studies provide direct evidence that adult satellite cells derive from progenitors that first express the myogenic determination gene Myf5 during fetal stages of myogenesis.
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Affiliation(s)
- Stefano Biressi
- Paul F. Glenn Laboratories for the Biology of Aging and Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, USA
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158
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Embryonic founders of adult muscle stem cells are primed by the determination gene Mrf4. Dev Biol 2013; 381:241-55. [PMID: 23623977 DOI: 10.1016/j.ydbio.2013.04.018] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 03/27/2013] [Accepted: 04/17/2013] [Indexed: 01/15/2023]
Abstract
Skeletal muscle satellite cells play a critical role during muscle growth, homoeostasis and regeneration. Selective induction of the muscle determination genes Myf5, Myod and Mrf4 during prenatal development can potentially impact on the reported functional heterogeneity of adult satellite cells. Accordingly, expression of Myf5 was reported to diminish the self-renewal potential of the majority of satellite cells. In contrast, virtually all adult satellite cells showed antecedence of Myod activity. Here we examine the priming of myogenic cells by Mrf4 throughout development. Using a Cre-lox based genetic strategy and novel highly sensitive Pax7 reporter alleles compared to the ubiquitous Rosa26-based reporters, we show that all adult satellite cells, independently of their anatomical location or embryonic origin, have been primed for Mrf4 expression. Given that Mrf4Cre and Mrf4nlacZ are active exclusively in progenitors during embryogenesis, whereas later expression is restricted to differentiated myogenic cells, our findings suggest that adult satellite cells emerge from embryonic founder cells in which the Mrf4 locus was activated. Therefore, this level of myogenic priming by induction of Mrf4, does not compromise the potential of the founder cells to assume an upstream muscle stem cell state. We propose that embryonic myogenic cells and the majority of adult muscle stem cells form a lineage continuum.
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159
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Kuroda K, Kuang S, Taketo MM, Rudnicki MA. Canonical Wnt signaling induces BMP-4 to specify slow myofibrogenesis of fetal myoblasts. Skelet Muscle 2013; 3:5. [PMID: 23497616 PMCID: PMC3602004 DOI: 10.1186/2044-5040-3-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 02/15/2013] [Indexed: 11/24/2022] Open
Abstract
Background The Wnts are secreted proteins that play important roles in skeletal myogenesis, muscle fiber type diversification, neuromuscular junction formation and muscle stem cell function. How Wnt proteins orchestrate such diverse activities remains poorly understood. Canonical Wnt signaling stabilizes β-catenin, which subsequently translocate to the nucleus to activate the transcription of TCF/LEF family genes. Methods We employed TCF-reporter mice and performed analysis of embryos and of muscle groups. We further isolated fetal myoblasts and performed cell and molecular analyses. Results We found that canonical Wnt signaling is strongly activated during fetal myogenesis and weakly activated in adult muscles limited to the slow myofibers. Muscle-specific transgenic expression of a stabilized β-catenin protein led to increased oxidative myofibers and reduced muscle mass, suggesting that canonical Wnt signaling promotes slow fiber types and inhibits myogenesis. By TCF-luciferase reporter assay, we identified Wnt-1 and Wnt-3a as potent activators of canonical Wnt signaling in myogenic progenitors. Consistent with in vivo data, constitutive overexpression of Wnt-1 or Wnt-3a inhibited the proliferation of both C2C12 and primary myoblasts. Surprisingly, Wnt-1 and Wnt-3a overexpression up-regulated BMP-4, and inhibition of BMP-4 by shRNA or recombinant Noggin protein rescued the myogenic inhibitory effect of Wnt-1 and Wnt-3a. Importantly, Wnt-3a or BMP-4 recombinant proteins promoted slow myosin heavy chain expression during myogenic differentiation of fetal myoblasts. Conclusions These results demonstrate a novel interaction between canonical Wnt and BMP signaling that induces myogenic differentiation towards slow muscle phenotype.
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Affiliation(s)
- Kazuki Kuroda
- Sprott Center for Stem Cell Research, Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, ON, K1H 8L6, Canada.
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160
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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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161
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Barreiro E, Sznajder JI. Epigenetic regulation of muscle phenotype and adaptation: a potential role in COPD muscle dysfunction. J Appl Physiol (1985) 2013; 114:1263-72. [PMID: 23305984 DOI: 10.1152/japplphysiol.01027.2012] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Quadriceps muscle dysfunction occurs in one-third of patients with chronic obstructive pulmonary disease (COPD) in very early stages of their condition, even prior to the development of airway obstruction. Among several factors, deconditioning and muscle mass loss are the most relevant contributing factors leading to this dysfunction. Moreover, epigenetics, defined as the process whereby gene expression is regulated by heritable mechanisms that do not affect DNA sequence, could be involved in the susceptibility to muscle dysfunction, pathogenesis, and progression. Herein, we review the role of epigenetic mechanisms in muscle development and adaptation to environmental factors such as immobilization and exercise, and their implications in the pathophysiology and susceptibility to muscle dysfunction in COPD. The epigenetic modifications identified so far include DNA methylation, histone acetylation and methylation, and non-coding RNAs such as microRNAs (miRNAs). In the present review, we describe the specific contribution of epigenetic mechanisms to the regulation of embryonic myogenesis, muscle structure and metabolism, immobilization, and exercise, and in muscles of COPD patients. Events related to muscle development and regeneration and the response to exercise and immobilization are tightly regulated by epigenetic mechanisms. These environmental factors play a key role in the outcome of muscle mass and function as well as in the susceptibility to muscle dysfunction in COPD. Future research remains to be done to shed light on the specific target pathways of miRNA function and other epigenetic mechanisms in the susceptibility, pathogenesis, and progression of COPD muscle dysfunction.
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Affiliation(s)
- Esther Barreiro
- Respiratory Medicine Department-Lung Cancer Research Group, Institute of Medical Research of Hospital del Mar (IMIMHospital del Mar, Barcelona Biomedical Research Park (PRBB Barcelona, Spain.
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162
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Two distinct muscle progenitor populations coexist throughout amniote development. Dev Biol 2013; 373:141-8. [DOI: 10.1016/j.ydbio.2012.10.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 10/12/2012] [Indexed: 11/19/2022]
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163
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Hu JKH, McGlinn E, Harfe BD, Kardon G, Tabin CJ. Autonomous and nonautonomous roles of Hedgehog signaling in regulating limb muscle formation. Genes Dev 2012; 26:2088-102. [PMID: 22987639 DOI: 10.1101/gad.187385.112] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Muscle progenitor cells migrate from the lateral somites into the developing vertebrate limb, where they undergo patterning and differentiation in response to local signals. Sonic hedgehog (Shh) is a secreted molecule made in the posterior limb bud that affects patterning and development of multiple tissues, including skeletal muscles. However, the cell-autonomous and non-cell-autonomous functions of Shh during limb muscle formation have remained unclear. We found that Shh affects the pattern of limb musculature non-cell-autonomously, acting through adjacent nonmuscle mesenchyme. However, Shh plays a cell-autonomous role in maintaining cell survival in the dermomyotome and initiating early activation of the myogenic program in the ventral limb. At later stages, Shh promotes slow muscle differentiation cell-autonomously. In addition, Shh signaling is required cell-autonomously to regulate directional muscle cell migration in the distal limb. We identify neuroepithelial cell transforming gene 1 (Net1) as a downstream target and effector of Shh signaling in that context.
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Affiliation(s)
- Jimmy Kuang-Hsien Hu
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
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164
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Mourikis P, Gopalakrishnan S, Sambasivan R, Tajbakhsh S. Cell-autonomous Notch activity maintains the temporal specification potential of skeletal muscle stem cells. Development 2012; 139:4536-48. [PMID: 23136394 DOI: 10.1242/dev.084756] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
During organogenesis, a continuum of founder stem cells produces temporally distinct progeny until development is complete. Similarly, in skeletal myogenesis, phenotypically and functionally distinct myoblasts and differentiated cells are generated during development. How this occurs in muscle and other tissues in vertebrates remains largely unclear. We showed previously that committed cells are required for maintaining muscle stem cells. Here we show that active Notch signalling specifies a subpopulation of myogenic cells with high Pax7 expression. By genetically modulating Notch activity, we demonstrate that activated Notch (NICD) blocks terminal differentiation in an Rbpj-dependent manner that is sufficient to sustain stem/progenitor cells throughout embryogenesis, despite the absence of committed progeny. Although arrested in lineage progression, NICD-expressing cells of embryonic origin progressively mature and adopt characteristics of foetal myogenic cells, including expression of the foetal myogenesis regulator Nfix. siRNA-mediated silencing of NICD promotes the temporally appropriate foetal myogenic fate in spite of expression of markers for multiple cell types. We uncover a differential effect of Notch, whereby high Notch activity is associated with stem/progenitor cell expansion in the mouse embryo, yet it promotes reversible cell cycle exit in the foetus and the appearance of an adult muscle stem cell state. We propose that active Notch signalling is sufficient to sustain an upstream population of muscle founder stem cells while suppressing differentiation. Significantly, Notch does not override other signals that promote temporal myogenic cell fates during ontology where spatiotemporal developmental cues produce distinct phenotypic classes of myoblasts.
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Affiliation(s)
- Philippos Mourikis
- Stem Cells and Development, Department of Developmental Biology, CNRS URA 2578, Institut Pasteur, 25 rue du Dr Roux, 75105 Paris, France
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165
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Relaix F, Zammit PS. Satellite cells are essential for skeletal muscle regeneration: the cell on the edge returns centre stage. Development 2012; 139:2845-56. [PMID: 22833472 DOI: 10.1242/dev.069088] [Citation(s) in RCA: 550] [Impact Index Per Article: 45.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Following their discovery in 1961, it was speculated that satellite cells were dormant myoblasts, held in reserve until required for skeletal muscle repair. Evidence for this accumulated over the years, until the link between satellite cells and the myoblasts that appear during muscle regeneration was finally established. Subsequently, it was demonstrated that, when grafted, satellite cells could also self-renew, conferring on them the coveted status of 'stem cell'. The emergence of other cell types with myogenic potential, however, questioned the precise role of satellite cells. Here, we review recent recombination-based studies that have furthered our understanding of satellite cell biology. The clear consensus is that skeletal muscle does not regenerate without satellite cells, confirming their pivotal and non-redundant role.
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166
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Abstract
Satellite cells represent the primary population of stem cells resident in skeletal muscle. These adult muscle stem cells facilitate the postnatal growth, remodeling, and regeneration of skeletal muscle. Given the remarkable regenerative potential of satellite cells, there is great promise for treatment of muscle pathologies such as the muscular dystrophies with this cell population. Various protocols have been developed which allow for isolation, enrichment, and expansion of satellite cell derived muscle stem cells. However, isolated satellite cells have yet to translate into effective modalities for therapeutic intervention. Broadening our understanding of satellite cells and their niche requirements should improve our in vivo and ex vivo manipulation of these cells to expedite their use for regeneration of diseased muscle. This review explores the fates of satellite cells as determined by their molecular signatures, ontogeny, and niche dependent programming.
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Affiliation(s)
- Arif Aziz
- Sprott Center for Stem Cell Research, Regenerative Medicine Program, Ottawa Hospital Research Institute, 501 Smyth Rd, Mailbox 511, Ottawa, ON, Canada K1H 8L6
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167
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von Maltzahn J, Chang NC, Bentzinger CF, Rudnicki MA. Wnt signaling in myogenesis. Trends Cell Biol 2012; 22:602-9. [PMID: 22944199 DOI: 10.1016/j.tcb.2012.07.008] [Citation(s) in RCA: 268] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Revised: 07/24/2012] [Accepted: 07/30/2012] [Indexed: 02/05/2023]
Abstract
The formation of skeletal muscle is a tightly regulated process that is critically modulated by Wnt signaling. Myogenesis is dependent on the precise and dynamic integration of multiple Wnt signals allowing self-renewal and progression of muscle precursors in the myogenic lineage. Dysregulation of Wnt signaling can lead to severe developmental defects and perturbation of muscle homeostasis. Recent work has revealed novel roles for the non-canonical planar cell polarity (PCP) and AKT/mTOR pathways in mediating the effects of Wnt on skeletal muscle. In this review, we discuss the role of Wnt signaling in myogenesis and in regulating the homeostasis of adult muscle.
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Affiliation(s)
- Julia von Maltzahn
- Sprott Center for Stem Cell Research, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
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168
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Fiorotto M. The making of a muscle. THE BIOCHEMIST 2012; 34:4-11. [PMID: 28190934 PMCID: PMC5298863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The skeletal musculature is usually thought of as the primary organ of locomotion, and, like the tyres of a high-performance racing car, their composition, design, preparation and plasticity can make the difference between winner and 'wannabe'. The similarities do not end there, however. Their primary components (cells of the mesodermal layer in the embryo and latex from the rubber tree) begin their existence in locations that can be quite distant from their final point of use and in forms that bear no resemblance to the final product. Their differentiation from primary material to final product entails extensive processing, and the integration of other materials and structures are essential to ensure their function. A fundamental difference, however, is that, in the case of muscle, once the embryo is formed, the progression from relatively undifferentiated mesodermal cells to the final structures is on autopilot, provided there are no contextual aberrations either from genetic or environmental causes. Our current understanding of how muscles develop is a synthesis of observations made on a wide array of organisms, including nematode worms, fruitflies, fish, frogs, birds and various mammals, as well as from the in vitro study of cells isolated from these species. The study of myogenesis in mammals, although less amenable to experimental manipulation, has been facilitated by the recent advances in mouse genetic engineering which has enabled the function of individual genes and cell types to be investigated, as well as the lineage of cells to be traced back to their origin. In this rapid trek through the life of a muscle, how the production of a mature functional muscle from its early inception is orchestrated will be outlined in exceedingly broad strokes so as to convey the wide range of processes that must be engaged in order to generate a functional muscle. Hopefully, enough information will be provided to encourage those interested to explore further.
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Affiliation(s)
- Marta Fiorotto
- USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine
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169
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Hong GM, Bain LJ. Arsenic exposure inhibits myogenesis and neurogenesis in P19 stem cells through repression of the β-catenin signaling pathway. Toxicol Sci 2012; 129:146-56. [PMID: 22641621 DOI: 10.1093/toxsci/kfs186] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Epidemiological studies have correlated embryonic arsenic exposure with adverse developmental outcomes such as stillbirths, neonatal mortality, and low birth weight. Additionally, arsenic exposure reduces neuronal cell migration and maturation, and reduces skeletal muscle cell formation, alters muscle fiber subtype, and changes locomotor activity. This study used P19 mouse embryonic stem cells to examine whether arsenic exposure could alter their differentiation into skeletal muscles and neurons. When P19 cells were exposed to 0.1, 0.5, or 1.0 μM sodium arsenite, embryoid body (EB) formation was not altered. However, arsenic suppressed their differentiation into muscles and neurons, as evidenced by morphological changes accompanied by a significant reduction in myosin heavy chain and Tuj1 expression. Real-time PCR, immunofluorescence, and immunoblotting were used to confirm that the altered differentiation was due to the repression of muscle- and neuron-specific transcription factors such as Pax3, Myf5, MyoD, myogenin, neurogenin 1, neurogenin 2, and NeuroD in the arsenite-exposed cells. The reductions in transcription factors expression appear to be caused by repressed Wnt/β-catenin signaling pathways in early embryogenesis, as evidenced by decreased β-catenin expression in the arsenic-exposed EBs on differentiation days 2 and 5. Interestingly, the expression of Nanog, a transcription factor that maintains the pluripotency of stem cells, was increased after arsenite exposure, indicating that arsenite inhibits their differentiation but not proliferation. This study demonstrates that arsenic can perturb the embryonic differentiation process by repressing the Wnt/β-catenin signaling pathway. More importantly, this study may provide insight into how arsenic exposure affects skeletal and neuronal differentiation during embryogenesis.
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Affiliation(s)
- Gia-Ming Hong
- Environmental Toxicology Graduate Program, Clemson University, 132 Long Hall, Clemson, South Carolina 29634, USA
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170
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Soleimani VD, Punch VG, Kawabe YI, Jones AE, Palidwor GA, Porter CJ, Cross JW, Carvajal JJ, Kockx CEM, van IJcken WFJ, Perkins TJ, Rigby PWJ, Grosveld F, Rudnicki MA. Transcriptional dominance of Pax7 in adult myogenesis is due to high-affinity recognition of homeodomain motifs. Dev Cell 2012; 22:1208-20. [PMID: 22609161 DOI: 10.1016/j.devcel.2012.03.014] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Revised: 01/20/2012] [Accepted: 03/28/2012] [Indexed: 01/08/2023]
Abstract
Pax3 and Pax7 regulate stem cell function in skeletal myogenesis. However, molecular insight into their distinct roles has remained elusive. Using gene expression data combined with genome-wide binding-site analysis, we show that both Pax3 and Pax7 bind identical DNA motifs and jointly activate a large panel of genes involved in muscle stem cell function. Surprisingly, in adult myoblasts Pax3 binds a subset (6.4%) of Pax7 targets. Despite a significant overlap in their transcriptional network, Pax7 regulates distinct panels of genes involved in the promotion of proliferation and inhibition of myogenic differentiation. We show that Pax7 has a higher binding affinity to the homeodomain-binding motif relative to Pax3, suggesting that intrinsic differences in DNA binding contribute to the observed functional difference between Pax3 and Pax7 binding in myogenesis. Together, our data demonstrate distinct attributes of Pax7 function and provide mechanistic insight into the nonredundancy of Pax3 and Pax7 in muscle development.
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Affiliation(s)
- Vahab D Soleimani
- Sprott Centre for Stem Cell Research, Ottawa Hospital Research Institute, and Department of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
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171
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Belyea B, Kephart JG, Blum J, Kirsch DG, Linardic CM. Embryonic signaling pathways and rhabdomyosarcoma: contributions to cancer development and opportunities for therapeutic targeting. Sarcoma 2012; 2012:406239. [PMID: 22619564 PMCID: PMC3350847 DOI: 10.1155/2012/406239] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2011] [Accepted: 01/17/2012] [Indexed: 11/18/2022] Open
Abstract
Rhabdomyosarcoma is the most common soft tissue sarcoma of childhood and adolescence, accounting for approximately 7% of childhood cancers. Current therapies include nonspecific cytotoxic chemotherapy regimens, radiation therapy, and surgery; however, these multimodality strategies are unsuccessful in the majority of patients with high-risk disease. It is generally believed that these tumors represent arrested or aberrant skeletal muscle development, and, accordingly, developmental signaling pathways critical to myogenesis such as Notch, WNT, and Hedgehog may represent new therapeutic targets. In this paper, we summarize the current preclinical studies linking these embryonic pathways to rhabdomyosarcoma tumorigenesis and provide support for the investigation of targeted therapies in this embryonic cancer.
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Affiliation(s)
- Brian Belyea
- Department of Pediatrics, Duke University Medical Center, Durham, NC 27710, USA
- Department of Pediatrics, University of Virginia, Charlottesville, VA 22908, USA
| | - Julie Grondin Kephart
- Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Jordan Blum
- Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - David G. Kirsch
- Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA
| | - Corinne M. Linardic
- Department of Pediatrics, Duke University Medical Center, Durham, NC 27710, USA
- Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA
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172
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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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173
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Abstract
The fusion of myoblasts into multinucleate syncytia plays a fundamental role in muscle function, as it supports the formation of extended sarcomeric arrays, or myofibrils, within a large volume of cytoplasm. Principles learned from the study of myoblast fusion not only enhance our understanding of myogenesis, but also contribute to our perspectives on membrane fusion and cell-cell fusion in a wide array of model organisms and experimental systems. Recent studies have advanced our views of the cell biological processes and crucial proteins that drive myoblast fusion. Here, we provide an overview of myoblast fusion in three model systems that have contributed much to our understanding of these events: the Drosophila embryo; developing and regenerating mouse muscle; and cultured rodent muscle cells.
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Affiliation(s)
- Susan M Abmayr
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA.
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174
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Amini-Nik S, Glancy D, Boimer C, Whetstone H, Keller C, Alman BA. Pax7 expressing cells contribute to dermal wound repair, regulating scar size through a β-catenin mediated process. Stem Cells 2012; 29:1371-9. [PMID: 21739529 DOI: 10.1002/stem.688] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
During skin wound healing, fibroblast-like cells reconstitute the dermal compartment of the repaired skin filling the wound gap. A subset of these cells are transcriptionally active for β-catenin/T-cell factor (TCF) signaling during the proliferative phase of the repair process, and β-catenin levels control the size of the scar that ultimately forms by regulating the number of dermal fibroblasts. Here, we performed cell lineage studies to reveal a source of the dermal cells in which β-catenin signaling is activated during wound repair. Using a reporter mouse, we found that cells in the early wound in which TCF-dependent transcription is activated express genes involved in muscle development. Using mice in which cells express Pax7 (muscle progenitors) or Mck (differentiated myocytes) are permanently labeled, we showed that one quarter of dermal cells in the healing wound are Pax7 expressing progeny, but none are Mck progeny. Removing one allele of β-catenin in Pax7 expressing progeny resulted in a significantly smaller scar size with fewer Pax7 expressing progeny cell contributing to wound repair. During wound healing, β-catenin activation causes muscle satellite cells to adopt a fibrotic phenotype and this is a source of dermal cells in the repair process.
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Affiliation(s)
- Saeid Amini-Nik
- Program in Developmental and Stem Cell Biology, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
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175
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Bentzinger CF, Wang YX, Rudnicki MA. Building muscle: molecular regulation of myogenesis. Cold Spring Harb Perspect Biol 2012; 4:4/2/a008342. [PMID: 22300977 DOI: 10.1101/cshperspect.a008342] [Citation(s) in RCA: 719] [Impact Index Per Article: 59.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The genesis of skeletal muscle during embryonic development and postnatal life serves as a paradigm for stem and progenitor cell maintenance, lineage specification, and terminal differentiation. An elaborate interplay of extrinsic and intrinsic regulatory mechanisms controls myogenesis at all stages of development. Many aspects of adult myogenesis resemble or reiterate embryonic morphogenetic episodes, and related signaling mechanisms control the genetic networks that determine cell fate during these processes. An integrative view of all aspects of myogenesis is imperative for a comprehensive understanding of muscle formation. This article provides a holistic overview of the different stages and modes of myogenesis with an emphasis on the underlying signals, molecular switches, and genetic networks.
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Affiliation(s)
- C Florian Bentzinger
- The Sprott Centre for Stem Cell Research, Regenerative Medicine Program, Ottawa Health Research Institute, Ottawa, Ontario, Canada
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176
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Tumbar T. Ontogeny and Homeostasis of Adult Epithelial Skin Stem Cells. Stem Cell Rev Rep 2012; 8:10.1007/s12015-012-9348-9. [PMID: 22290419 PMCID: PMC4103971 DOI: 10.1007/s12015-012-9348-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Mouse epithelial skin stem cells constitute an important model system for understanding the dynamics of stem cell emergence and behavior in an intact vertebrate tissue. Recent published work defined discrete populations of epithelial stem cells in the adult skin epithelium, which reside in the hair follicle bulge and germ, isthmus, sebaceous gland and inter-follicular epidermis. Adult epidermal and hair follicle stem cells seem to adopt mostly symmetric or unidirectional fate decisions of either one of two possible fates: (1) differentiate and be lost from the tissue or (2) expand symmetrically to self-renew. Asymmetric divisions appear to be mostly implicated in differentiation and stratification of the epidermis. While mechanisms of adult stem cell homeostasis begin to be unraveled, the embryonic origin of the adult epithelial skin stem cells is poorly understood. Recent studies reported Sox9, Lgr6, and Runx1 expression in subpopulations of cells in the embryonic hair placode. These subpopulations seem to act as precursors of different classes of adult epithelial stem cells. In particular, Runx1 regulates a Wnt-mediated cross-talk between the nascent adult-type hair follicle stem cells and their environment, which is essential for timely stem cell emergence, proper maturation, long-term differentiation potential, and maintenance. The new data begin to define the basic dynamics and regulatory pathways governing the ontogeny of adult epithelial stem cells.
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Affiliation(s)
- Tudorita Tumbar
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA,
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177
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Makarenkova HP, Meech R. Barx homeobox family in muscle development and regeneration. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 297:117-73. [PMID: 22608559 DOI: 10.1016/b978-0-12-394308-8.00004-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Homeobox transcription factors are key intrinsic regulators of myogenesis. In studies spanning several years, we have characterized the homeobox factor Barx2 as a novel marker for muscle progenitor cells and an important regulator of muscle growth and repair. In this review, we place the expression and function of Barx2 and its paralogue Barx1 in context with other muscle-expressed homeobox factors in both embryonic and adult myogenesis. We also describe the structure and regulation of Barx genes and possible gene/disease associations. The functional domains of Barx proteins, their molecular interactions, and cellular functions are presented with particular emphasis on control of genes and processes involved in myogenic differentiation. Finally, we describe the patterns of Barx gene expression in vivo and the phenotypes of various Barx gene perturbation models including null mice. We focus on the Barx2 null mouse model, which has demonstrated the critical roles of Barx2 in postnatal myogenesis including muscle maintenance during aging, and regeneration of acute and chronic muscle injury.
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Affiliation(s)
- Helen P Makarenkova
- The Neurobiology Department, Scripps Research Institute, La Jolla, California, USA
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178
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Chakkalakal J, Brack A. Extrinsic Regulation of Satellite Cell Function and Muscle Regeneration Capacity during Aging. ACTA ACUST UNITED AC 2012; Suppl 11:001. [PMID: 24678443 PMCID: PMC3965255 DOI: 10.4172/2157-7633.s11-001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Optimal regeneration of skeletal muscle in response to injury requires the contribution of tissue resident stem cells termed satellite cells. Normally residing at the interface between the muscle fiber and overlying basal lamina it is generally understood with age the satellite cell pool exhibits decline both in number and function. Over the past decade mechanisms that contribute to these declines have begun to emerge. Implicit in aged-related satellite cell dysfunction and decline is the involvement of signals from the environment. Many of the signals that become deregulated with age have conserved functions during distinct stages of muscle fiber formation both in early development and regeneration. In particular, modulations in Wnt, TGFβ, Notch and FGF emanating from aged skeletal muscle fibers or the systemic milieu have emerged as age-related alterations that significantly impact both the maintenance of the satellite cell pool and skeletal muscle regenerative efficacy. In this review we will summarize how the aforementioned pathways contribute to skeletal muscle development and regeneration. We will then discuss deregulation of these cascades with age and how they contribute to satellite cell depletion and dysfunction. The review will also summarize some of the challenges we face in trying to draw parallels between murine and human satellite cell aging. Finally, we will highlight the few examples whereby FDA approved drugs may be exploited to modulate specific signaling cascades in effort to preserve skeletal muscle regenerative function with age.
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Affiliation(s)
- Jv Chakkalakal
- Center of Regenerative Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA
| | - As Brack
- Center of Regenerative Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA ; Harvard Stem Cell Institute, 135 Massachusetts Avenue, Boston, Massachusetts 02138, USA
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179
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Takagaki Y, Yamagishi H, Matsuoka R. Factors Involved in Signal Transduction During Vertebrate Myogenesis. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 296:187-272. [DOI: 10.1016/b978-0-12-394307-1.00004-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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180
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Abstract
Satellite cells are a heterogeneous population of stem and progenitor cells that are required for the growth, maintenance and regeneration of skeletal muscle. The transcription factors paired-box 3 (PAX3) and PAX7 have essential and overlapping roles in myogenesis. PAX3 acts to specify embryonic muscle precursors, whereas PAX7 enforces the satellite cell myogenic programme while maintaining the undifferentiated state. Recent experiments have suggested that PAX7 is dispensable in adult satellite cells. However, these findings are controversial, and the issue remains unresolved.
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181
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Yvernogeau L, Auda-Boucher G, Fontaine-Perus J. Limb bud colonization by somite-derived angioblasts is a crucial step for myoblast emigration. Development 2011; 139:277-87. [PMID: 22129828 DOI: 10.1242/dev.067678] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have combined the use of mouse genetic strains and the mouse-into-chicken chimera system to determine precisely the sequence of forelimb colonization by presomitic mesoderm (PSM)-derived myoblasts and angioblasts, and the possible role of this latter cell type in myoblast guidance. By creating a new Flk1/Pax3 double reporter mouse line, we have established the precise timetable for angioblast and myoblast delamination/migration from the somite to the limb bud. This timetable was conserved when mouse PSM was grafted into a chicken host, which further validates the experimental model. The use of Pax3(GFP/GFP) knockout mice showed that establishment of vascular endothelial and smooth muscle cells (SMCs) is not compromised by the absence of Pax3. Of note, Pax3(GFP/GFP) knockout mouse PSM-derived cells can contribute to aortic, but not to limb, SMCs that are derived from the somatopleure. Finally, using the Flk1(lacZ)(/)(lacZ) knockout mouse, we show that, in the absence of angioblast and vascular network formation, myoblasts are prevented from migrating into the limb. Taken together, our study establishes for the first time the time schedule for endothelial and skeletal muscle cell colonization in the mouse limb bud and establishes the absolute requirement of endothelial cells for myoblast delamination and migration to the limb. It also reveals that cells delaminating from the somites display marked differentiation traits, suggesting that if a common progenitor exists, its lifespan is extremely short and restricted to the somite.
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Affiliation(s)
- Laurent Yvernogeau
- Université de Nantes, CNRS 6204, 2 rue de la Houssinière, 44322 Nantes, France.
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182
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Richard AF, Demignon J, Sakakibara I, Pujol J, Favier M, Strochlic L, Le Grand F, Sgarioto N, Guernec A, Schmitt A, Cagnard N, Huang R, Legay C, Guillet-Deniau I, Maire P. Genesis of muscle fiber-type diversity during mouse embryogenesis relies on Six1 and Six4 gene expression. Dev Biol 2011; 359:303-20. [DOI: 10.1016/j.ydbio.2011.08.010] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 07/22/2011] [Accepted: 08/15/2011] [Indexed: 01/28/2023]
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183
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Murphy MM, Lawson JA, Mathew SJ, Hutcheson DA, Kardon G. Satellite cells, connective tissue fibroblasts and their interactions are crucial for muscle regeneration. Development 2011; 138:3625-37. [PMID: 21828091 DOI: 10.1242/dev.064162] [Citation(s) in RCA: 807] [Impact Index Per Article: 62.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Muscle regeneration requires the coordinated interaction of multiple cell types. Satellite cells have been implicated as the primary stem cell responsible for regenerating muscle, yet the necessity of these cells for regeneration has not been tested. Connective tissue fibroblasts also are likely to play a role in regeneration, as connective tissue fibrosis is a hallmark of regenerating muscle. However, the lack of molecular markers for these fibroblasts has precluded an investigation of their role. Using Tcf4, a newly identified fibroblast marker, and Pax7, a satellite cell marker, we found that after injury satellite cells and fibroblasts rapidly proliferate in close proximity to one another. To test the role of satellite cells and fibroblasts in muscle regeneration in vivo, we created Pax7(CreERT2) and Tcf4(CreERT2) mice and crossed these to R26R(DTA) mice to genetically ablate satellite cells and fibroblasts. Ablation of satellite cells resulted in a complete loss of regenerated muscle, as well as misregulation of fibroblasts and a dramatic increase in connective tissue. Ablation of fibroblasts altered the dynamics of satellite cells, leading to premature satellite cell differentiation, depletion of the early pool of satellite cells, and smaller regenerated myofibers. Thus, we provide direct, genetic evidence that satellite cells are required for muscle regeneration and also identify resident fibroblasts as a novel and vital component of the niche regulating satellite cell expansion during regeneration. Furthermore, we demonstrate that reciprocal interactions between fibroblasts and satellite cells contribute significantly to efficient, effective muscle regeneration.
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Affiliation(s)
- Malea M Murphy
- Department of Human Genetics, University of Utah, 15 North 2030 East, Salt Lake City, UT 84112, USA
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184
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Pericytes resident in postnatal skeletal muscle differentiate into muscle fibres and generate satellite cells. Nat Commun 2011; 2:499. [PMID: 21988915 DOI: 10.1038/ncomms1508] [Citation(s) in RCA: 326] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Accepted: 09/13/2011] [Indexed: 01/07/2023] Open
Abstract
Skeletal muscle fibres form by fusion of mesoderm progenitors called myoblasts. After birth, muscle fibres do not increase in number but continue to grow in size because of fusion of satellite cells, the postnatal myogenic cells, responsible for muscle growth and regeneration. Numerous studies suggest that, on transplantation, non-myogenic cells also may contribute to muscle regeneration. However, there is currently no evidence that such a contribution represents a natural developmental option of these non-myogenic cells, rather than a consequence of experimental manipulation resulting in cell fusion. Here we show that pericytes, transgenically labelled with an inducible Alkaline Phosphatase CreERT2, but not endothelial cells, fuse with developing myofibres and enter the satellite cell compartment during unperturbed postnatal development. This contribution increases significantly during acute injury or in chronically regenerating dystrophic muscle. These data show that pericytes, resident in small vessels of skeletal muscle, contribute to its growth and regeneration during postnatal life.
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185
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Zhao X, Mo D, Li A, Gong W, Xiao S, Zhang Y, Qin L, Niu Y, Guo Y, Liu X, Cong P, He Z, Wang C, Li J, Chen Y. Comparative analyses by sequencing of transcriptomes during skeletal muscle development between pig breeds differing in muscle growth rate and fatness. PLoS One 2011; 6:e19774. [PMID: 21637832 PMCID: PMC3102668 DOI: 10.1371/journal.pone.0019774] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Accepted: 04/05/2011] [Indexed: 01/25/2023] Open
Abstract
Understanding the dynamics of muscle transcriptome during development and between breeds differing in muscle growth is necessary to uncover the complex mechanism underlying muscle development. Herein, we present the first transcriptome-wide longissimus dorsi muscle development research concerning Lantang (LT, obese) and Landrace (LR, lean) pig breeds during 10 time-points from 35 days-post-coitus (dpc) to 180 days-post-natum (dpn) using Solexa/Illumina's Genome Analyzer. The data demonstrated that myogenesis was almost completed before 77 dpc, but the muscle phenotypes were still changed from 77 dpc to 28 dpn. Comparative analysis of the two breeds suggested that myogenesis started earlier but progressed more slowly in LT than in LR, the stages ranging from 49 dpc to 77 dpc are critical for formation of different muscle phenotypes. 595 differentially expressed myogenesis genes were identified, and their roles in myogenesis were discussed. Furthermore, GSK3B, IKBKB, ACVR1, ITGA and STMN1 might contribute to later myogenesis and more muscle fibers in LR than LT. Some myogenesis inhibitors (ID1, ID2, CABIN1, MSTN, SMAD4, CTNNA1, NOTCH2, GPC3 and HMOX1) were higher expressed in LT than in LR, which might contribute to more slow muscle differentiation in LT than in LR. We also identified several genes which might contribute to intramuscular adipose differentiation. Most important, we further proposed a novel model in which MyoD and MEF2A controls the balance between intramuscular adipogenesis and myogenesis by regulating CEBP family; Myf5 and MEF2C are essential during the whole myogenesis process while MEF2D affects muscle growth and maturation. The MRFs and MEF2 families are also critical for the phenotypic differences between the two pig breeds. Overall, this study contributes to elucidating the mechanism underlying muscle development, which could provide valuable information for pig meat quality improvement. The raw data have been submitted to Gene Expression Omnibus (GEO) under series GSE25406.
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Affiliation(s)
- Xiao Zhao
- State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
| | - Delin Mo
- State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
| | - Anning Li
- State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
| | - Wen Gong
- State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
| | - Shuqi Xiao
- State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
| | - Yue Zhang
- State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
| | - Limei Qin
- State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
| | - Yuna Niu
- State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
| | - Yunxue Guo
- State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
| | - Xiaohong Liu
- State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
| | - Peiqing Cong
- State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
| | - Zuyong He
- State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
| | - Chong Wang
- College of Animal Science, South China of Agricultural University, Guangzhou, Guangdong, People's Republic of China
| | - Jiaqi Li
- College of Animal Science, South China of Agricultural University, Guangzhou, Guangdong, People's Republic of China
| | - Yaosheng Chen
- State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
- * E-mail:
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186
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Dedeic Z, Cetera M, Cohen TV, Holaska JM. Emerin inhibits Lmo7 binding to the Pax3 and MyoD promoters and expression of myoblast proliferation genes. J Cell Sci 2011; 124:1691-702. [DOI: 10.1242/jcs.080259] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
X-linked Emery–Dreifuss muscular dystrophy (X-EDMD) is caused by mutations in the inner nuclear membrane protein emerin. Previous studies have shown that emerin binds to and inhibits the activity of LIM domain only 7 (Lmo7), a transcription factor that regulates the expression of genes implicated in X-EDMD. Here, we analyzed Lmo7 function in C2C12 myoblast differentiation and its regulation by emerin. We found that Lmo7 was required for proper myoblast differentiation. Lmo7-downregulated myoblasts exhibited reduced expression of Pax3, Pax7, Myf5 and MyoD, whereas overexpression of GFP–Lmo7 increased the expression of MyoD and Myf5. Upon myotube formation, Lmo7 shuttled from the nucleus to the cytoplasm, concomitant with reduced expression of MyoD, Pax3 and Myf5. Importantly, we show that Lmo7 bound the Pax3, MyoD and Myf5 promoters both in C2C12 myoblasts and in vitro. Because emerin inhibited Lmo7 activity, we tested whether emerin competed with the MyoD promoter for binding to Lmo7 or whether emerin sequestered promoter-bound Lmo7 to the nuclear periphery. Supporting the competition model, emerin binding to Lmo7 inhibited Lmo7 binding to and activation of the MyoD and Pax3 promoters. These findings support the hypothesis that the functional interaction between emerin and Lmo7 is crucial for temporally regulating the expression of key myogenic differentiation genes.
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Affiliation(s)
- Zinaida Dedeic
- University of Chicago Committee on Developmental Biology, 920 East 58th Street, Chicago IL 60637, USA
| | - Maureen Cetera
- University of Chicago Committee on Developmental Biology, 920 East 58th Street, Chicago IL 60637, USA
| | - Tatiana V. Cohen
- Children's National Medical Center, Center for Genetic Medicine, 111 Michigan Avenue, Washington DC 20010-2970, USA
| | - James M. Holaska
- University of Chicago Committee on Developmental Biology, 920 East 58th Street, Chicago IL 60637, USA
- Department of Medicine, Section of Cardiology, The University of Chicago, 947 East 58th Street, Chicago, IL 60637, USA
- Committee on Genetics, Genomics and Systems Biology, 5812 S. Ellis Street, Chicago IL 60637, USA
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187
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Fitzsimons RB. Retinal vascular disease and the pathogenesis of facioscapulohumeral muscular dystrophy. A signalling message from Wnt? Neuromuscul Disord 2011; 21:263-71. [PMID: 21377364 DOI: 10.1016/j.nmd.2011.02.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The peripheral retinal vascular abnormality which accompanies FSHD belongs morphologically and clinically to a class of developmental 'retinal hypovasculopathies' caused by abnormalities of 'Wnt' signalling, which controls retinal angiogenesis. Wnt signalling is also fundamental to myogenesis. This paper integrates modern concepts of myogenic cell signalling and of transcription factor expression and control with data from the classic early ophthalmic and myology embryology literature. Together, they support an hypothesis that abnormalities of Wnt signalling, which activates myogenic programs and transcription factors in myoblasts and satellite cells, leads to defective muscle regeneration in FSHD. The selective vulnerability of different FSHD muscles (notably facial muscle, from the second branchial arch) might reflect patterns of transcription factor redundancies. This hypothesis has implications for FSHD research through study of transcription factors patterning in normal human muscles, and for autologous cell transplantation.
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188
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Hasson P. "Soft" tissue patterning: muscles and tendons of the limb take their form. Dev Dyn 2011; 240:1100-7. [PMID: 21438070 DOI: 10.1002/dvdy.22608] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/22/2011] [Indexed: 12/18/2022] Open
Abstract
The musculoskeletal system grants our bodies a vast range of movements. Because it is mainly composed of easily identifiable components, it serves as an ideal model to study patterning of the specific tissues that make up the organ. Surprisingly, although critical for the function of the musculoskeletal system, understanding of the embryonic processes that regulate muscle and tendon patterning is very limited. The recent identification of specific markers and the reagents stemming from them has revealed some of the molecular events regulating patterning of these soft tissues. This review will focus on some of the current work, with an emphasis on the roles of the muscle connective tissue, and discuss several key points that addressing them will advance our understanding of these patterning events.
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Affiliation(s)
- Peleg Hasson
- Department of Anatomy and Cell Biology, The Rappaport Family Institute for Research in the Medical Sciences, Technion-Israel Institute of Technology, Bat Galim, Haifa, Israel.
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189
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Mok GF, Sweetman D. Many routes to the same destination: lessons from skeletal muscle development. Reproduction 2011; 141:301-12. [PMID: 21183656 DOI: 10.1530/rep-10-0394] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The development and differentiation of vertebrate skeletal muscle provide an important paradigm to understand the inductive signals and molecular events controlling differentiation of specific cell types. Recent findings show that a core transcriptional network, initiated by the myogenic regulatory factors (MRFs; MYF5, MYOD, myogenin and MRF4), is activated by separate populations of cells in embryos in response to various signalling pathways. This review will highlight how cells from multiple distinct starting points can converge on a common set of regulators to generate skeletal muscle.
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Affiliation(s)
- Gi Fay Mok
- Division of Animal Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire LE12 5RD, UK
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190
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Deries M, Schweitzer R, Duxson MJ. Developmental fate of the mammalian myotome. Dev Dyn 2011; 239:2898-910. [PMID: 20865781 DOI: 10.1002/dvdy.22425] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The myotome is a segmented paraxial muscle present in all early vertebrate embryos, which in amniotes disappears in mid-embryogenesis, and is replaced by complex epaxial and hypaxial musculature. Little is known about how this transition occurs. Here, we describe the detailed morphogenesis of the epaxial muscles from the epaxial myotome, in rodent embryos. The results show there is no apoptosis of myotomal fibres during the transition, and that the epaxial muscles arise by translocation, re-orientation, and elongation of the myotomal myocytes followed by cleavage of the myotomal masses. Myotomal myocytes transit from a mononucleated to a multinucleated state just before onset of this transformation. Each newly-formed epaxial muscle anlagen includes populations of Pax3- and Pax7-positive muscle progenitors, with different distributions. Using transgenic mouse embryos bearing a GFP marker for Scleraxis, we show that tendon progenitors are tightly associated with the sides and ends of myotomal myocytes as they re-orient and elongate.
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Affiliation(s)
- Marianne Deries
- Department of Anatomy and Structural Biology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
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191
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Vickerman L, Neufeld S, Cobb J. Shox2 function couples neural, muscular and skeletal development in the proximal forelimb. Dev Biol 2011; 350:323-36. [DOI: 10.1016/j.ydbio.2010.11.031] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Revised: 11/13/2010] [Accepted: 11/29/2010] [Indexed: 11/28/2022]
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192
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Mathew SJ, Hansen JM, Merrell AJ, Murphy MM, Lawson JA, Hutcheson DA, Hansen MS, Angus-Hill M, Kardon G. Connective tissue fibroblasts and Tcf4 regulate myogenesis. Development 2011; 138:371-84. [PMID: 21177349 DOI: 10.1242/dev.057463] [Citation(s) in RCA: 231] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Muscle and its connective tissue are intimately linked in the embryo and in the adult, suggesting that interactions between these tissues are crucial for their development. However, the study of muscle connective tissue has been hindered by the lack of molecular markers and genetic reagents to label connective tissue fibroblasts. Here, we show that the transcription factor Tcf4 (transcription factor 7-like 2; Tcf7l2) is strongly expressed in connective tissue fibroblasts and that Tcf4(GFPCre) mice allow genetic manipulation of these fibroblasts. Using this new reagent, we find that connective tissue fibroblasts critically regulate two aspects of myogenesis: muscle fiber type development and maturation. Fibroblasts promote (via Tcf4-dependent signals) slow myogenesis by stimulating the expression of slow myosin heavy chain. Also, fibroblasts promote the switch from fetal to adult muscle by repressing (via Tcf4-dependent signals) the expression of developmental embryonic myosin and promoting (via a Tcf4-independent mechanism) the formation of large multinucleate myofibers. In addition, our analysis of Tcf4 function unexpectedly reveals a novel mechanism of intrinsic regulation of muscle fiber type development. Unlike other intrinsic regulators of fiber type, low levels of Tcf4 in myogenic cells promote both slow and fast myogenesis, thereby promoting overall maturation of muscle fiber type. Thus, we have identified novel extrinsic and intrinsic mechanisms regulating myogenesis. Most significantly, our data demonstrate for the first time that connective tissue is important not only for adult muscle structure and function, but is a vital component of the niche within which muscle progenitors reside and is a critical regulator of myogenesis.
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Affiliation(s)
- Sam J Mathew
- Department of Human Genetics, University of Utah, 15 North 2030 East, Salt Lake City, Utah 84112, USA
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193
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Molecular mechanisms of myoblast fusion across species. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 713:113-35. [PMID: 21432017 DOI: 10.1007/978-94-007-0763-4_8] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Skeletal muscle development, growth and regeneration depend on the ability of progenitor myoblasts to fuse to one another in a series of ordered steps. Whereas the cellular steps leading to the formation of a multinucleated myofiber are conserved in several model organisms, the molecular regulatory factors may vary. Understanding the common and divergent mechanisms regulating myoblast fusion in Drosophila melanogaster (fruit fly), Danio rerio (zebrafish) and Mus musculus (mouse) provides a better insight into the process of myoblast fusion than any of these models could provide alone. Deciphering the mechanisms of myoblast fusion from simpler to more complex organisms is of fundamental interest to skeletal muscle biology and may provide therapeutic avenues for various diseases that affect muscle.
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194
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Abstract
Muscle development, growth, and regeneration take place throughout vertebrate life. In amniotes, myogenesis takes place in four successive, temporally distinct, although overlapping phases. Understanding how embryonic, fetal, neonatal, and adult muscle are formed from muscle progenitors and committed myoblasts is an area of active research. In this review we examine recent expression, genetic loss-of-function, and genetic lineage studies that have been conducted in the mouse, with a particular focus on limb myogenesis. We synthesize these studies to present a current model of how embryonic, fetal, neonatal, and adult muscle are formed in the limb.
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Affiliation(s)
- Malea Murphy
- Department of Human Genetics, University of Utah, Salt Lake City, Utah, USA
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195
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Wang H, Bonnet A, Delfini MC, Kawakami K, Takahashi Y, Duprez D. Stable, conditional, and muscle-fiber-specific expression of electroporated transgenes in chick limb muscle cells. Dev Dyn 2010; 240:1223-32. [PMID: 21509896 DOI: 10.1002/dvdy.22498] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2010] [Indexed: 11/07/2022] Open
Abstract
Limb muscle formation is spread out over time and, consequently, muscle cells are not easy to target at any particular stages. We aimed to design a technique to study gene function in the different steps of limb muscle formation. We have associated transposon-mediated gene transfer and a tetracycline-dependent activation method with forelimb somite electroporation. In addition, we have established a new vector combining a differentiated-muscle-cell-specific promoter and the transposon system, which allows stable gene expression in limb differentiated muscle cells and not in muscle progenitors. Using these methods, we observed that conditional Fgf4 expression in muscle cells at the onset of fetal muscle differentiation and specific Fgf4 expression in differentiated muscle cells alter muscle fiber formation in chick limbs. Limb somite electroporation with these set of vectors allowing stable, conditional, and differentiated-muscle-specific expression of transgenes opens new perspectives for investigating gene function at various steps of limb muscle formation.
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Affiliation(s)
- Hui Wang
- CNRS, UMR7622, Biologie Moléculaire et Cellulaire du Développement, Université Pierre et Marie Curie, Paris, France
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196
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Lepper C, Fan CM. Inducible lineage tracing of Pax7-descendant cells reveals embryonic origin of adult satellite cells. Genesis 2010; 48:424-36. [PMID: 20641127 DOI: 10.1002/dvg.20630] [Citation(s) in RCA: 256] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
We have generated a mouse strain carrying a Cre-ER(T2) knock-in allele at the Pax7 locus, the Pax7(CE) allele (Lepper et al., 2009, Nature 460:627-631). Combining Pax7(CE) and the R26R(LacZ) Cre reporter allele, here we describe temporal-specific tamoxifen (tmx)-inducible lineage tracing of embryonic Pax7-expressing cells. In particular, we focus on the somitic lineage. Tmx-inducible Cre activity directed by the Pax7(CE) allele is similar to the endogenous Pax7 expression pattern. The somitic Pax7-expressing cells selectively marked at embryonic day 9.5 (E9.5) give rise to dorsal dermis and brown adipose tissue, in addition to dorsal aspects of trunk muscles and the diaphragm muscle. However, they do not contribute to ventral body wall and limb muscles. After E12.5, marked Pax7-expressing cells become lineage restricted to muscles. Descendants of these early marked Pax7-expressing cells begin to occupy sublaminal positions associated with the myofibers around E16.5, characteristic of embryonic satellite cells. Furthermore, they contribute to adult myofibers and regeneration competent satellite cells in the tibialis anterior muscle, providing evidence that some adult satellite cells are of embryonic origin.
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Affiliation(s)
- Christoph Lepper
- Department of Embryology, Carnegie Institution, Baltimore, Maryland, USA
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197
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Bismuth K, Relaix F. Genetic regulation of skeletal muscle development. Exp Cell Res 2010; 316:3081-6. [PMID: 20828559 DOI: 10.1016/j.yexcr.2010.08.018] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Revised: 08/30/2010] [Accepted: 08/31/2010] [Indexed: 11/16/2022]
Abstract
During development, skeletal muscles are established in a highly organized manner, which persists throughout life. Molecular and genetic experiments over the last decades have identified many developmental control genes critical for skeletal muscle formation. Developmental studies have shown that skeletal muscles of the body, limb and head have distinct embryonic and cellular origin, and the genetic regulation at work in these domains and during adult myogenesis are starting to be identified. In this review we will summarize the current knowledge on the regulatory circuits that lead to the establishment of skeletal muscle in these different anatomical regions.
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Affiliation(s)
- Keren Bismuth
- INSERM-UMR S 787-Myology Group, Avenir Team Mouse Molecular Genetics, UPMC- Faculté de Médecine Pitié-Salpêtrière, Institut de Myologie, 105 Boulevard de l'Hôpital, Paris, France
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198
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Bmp signaling at the tips of skeletal muscles regulates the number of fetal muscle progenitors and satellite cells during development. Dev Cell 2010; 18:643-54. [PMID: 20412778 DOI: 10.1016/j.devcel.2010.02.008] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2009] [Revised: 12/17/2009] [Accepted: 02/01/2010] [Indexed: 11/23/2022]
Abstract
Muscle progenitors, labeled by the transcription factor Pax7, are responsible for muscle growth during development. The signals that regulate the muscle progenitor number during myogenesis are unknown. We show, through in vivo analysis, that Bmp signaling is involved in regulating fetal skeletal muscle growth. Ectopic activation of Bmp signaling in chick limbs increases the number of fetal muscle progenitors and fibers, while blocking Bmp signaling reduces their numbers, ultimately leading to small muscles. The Bmp effect that we observed during fetal myogenesis is diametrically opposed to that previously observed during embryonic myogenesis and that deduced from in vitro work. We also show that Bmp signaling regulates the number of satellite cells during development. Finally, we demonstrate that Bmp signaling is active in a subpopulation of fetal progenitors and satellite cells at the extremities of muscles. Overall, our results show that Bmp signaling plays differential roles in embryonic and fetal myogenesis.
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199
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Bakkar N, Guttridge DC. NF-kappaB signaling: a tale of two pathways in skeletal myogenesis. Physiol Rev 2010; 90:495-511. [PMID: 20393192 DOI: 10.1152/physrev.00040.2009] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
NF-kappaB is a ubiquitiously expressed transcription factor that plays vital roles in innate immunity and other processes involving cellular survival, proliferation, and differentiation. Activation of NF-kappaB is controlled by an IkappaB kinase (IKK) complex that can direct either canonical (classical) NF-kappaB signaling by degrading the IkappaB inhibitor and releasing p65/p50 dimers to the nucleus, or causes p100 processing and nuclear translocation of RelB/p52 via a noncanonical (alternative) pathway. Under physiological conditions, NF-kappaB activity is transiently regulated, whereas constitutive activation of this transcription factor typically in the classical pathway is associated with a multitude of disease conditions, including those related to skeletal muscle. How NF-kappaB functions in muscle diseases is currently under intense investigation. Insight into this role of NF-kappaB may be gained by understanding at a more basic level how this transcription factor contributes to skeletal muscle cell differentiation. Recent data from knockout mice support that the classical NF-kappaB pathway functions as an inhibitor of skeletal myogenesis and muscle regeneration acting through multiple mechanisms. In contrast, alternative NF-kappaB signaling does not appear to be required for myofiber conversion, but instead functions in myotube homeostasis by regulating mitochondrial biogenesis. Additional knowledge of these signaling pathways in skeletal myogenesis should aid in the development of specific inhibitors that may be useful in treatments of muscle disorders.
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Affiliation(s)
- Nadine Bakkar
- Department of Molecular Virology, Immunology, and Medical Genetics, Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio 43210, USA
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200
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Abstract
PURPOSE OF REVIEW Skeletal muscle development serves as a paradigm for cell lineage specification and cell differentiation. Adult skeletal muscle has high regenerative capacity, with satellite cells the primary source of this capability. The present review describes recent findings on developmental and adult myogenesis with emphasis on emerging distinctions between various muscle groups and stages of myogenesis. RECENT FINDINGS Muscle progenitors of the body are derived from multipotent cells of the dermomyotome and express the transcription factors Pax3 and Pax7. These cells self-renew or induce expression of myogenic regulatory factors (MRFs) and differentiate. The roles of Pax3, Pax7 and specific myogenic regulatory factor progenitor populations in trunk and limb myogenesis have been identified through cell ablation in the mouse. Various head muscles and associated satellite cells have differing developmental origins, and rely on distinct combinations of transcriptional regulators, than trunk and limb muscles. Several genetic and sorting protocols demonstrate that satellite cells are heterogeneous with some possessing stem cell properties; the relative roles of lineage and niche in these properties are being explored. Although cellular mechanisms of developmental, postnatal and adult regenerative myogenesis are thought to be similar, recent studies reveal distinct genetic requirements for embryonic, fetal, postnatal and adult regenerative myogenesis. SUMMARY Genetic determinants of formation or repair of various muscles during different stages of myogenesis are unexpectedly diverse. Future studies should illuminate these differences, as well as mechanisms that underlie stem cell properties of satellite cells.
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Affiliation(s)
- Jong-Sun Kang
- Samsung Biomedical Research Institute, SungKyunKwan University School of Medicine, Suwon 440-746, South Korea
| | - Robert S. Krauss
- Department of Developmental and Regenerative Biology, Mount Sinai School of Medicine, New York, NY 10029, USA
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