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Carter MT, McMillan HJ, Tomin A, Weiss N. Compound heterozygous CACNA1H mutations associated with severe congenital amyotrophy. Channels (Austin) 2020; 13:153-161. [PMID: 31070086 PMCID: PMC6527065 DOI: 10.1080/19336950.2019.1614415] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Neuromuscular disorders encompass a wide range of conditions often associated with a genetic component. In the present study, we report a patient with severe infantile-onset amyotrophy in whom two compound heterozygous variants in the gene CACNA1H encoding for Cav3.2 T-type calcium channels were identified. Functional analysis of Cav3.2 variants revealed several alterations of the gating properties of the channel that were in general consistent with a loss-of-channel function. Taken together, these findings suggest that severe congenital amyoplasia may be related to CACNA1H and would represent a new phenotype associated with mutations in this gene.
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Affiliation(s)
- Melissa T Carter
- a Children's Hospital of Eastern Ontario Research Institute , University of Ottawa , Ottawa , Ontario , Canada
| | - Hugh J McMillan
- a Children's Hospital of Eastern Ontario Research Institute , University of Ottawa , Ottawa , Ontario , Canada
| | - Andriy Tomin
- b Institute of Organic Chemistry and Biochemistry , Czech Academy of Sciences , Prague , Czech Republic
| | - Norbert Weiss
- b Institute of Organic Chemistry and Biochemistry , Czech Academy of Sciences , Prague , Czech Republic
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2
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Sakamoto K. [A Cellular Pharmacological Approach to the Development of Drugs to Treat Muscle Wasting]. YAKUGAKU ZASSHI 2018; 138:1271-1275. [PMID: 30270271 DOI: 10.1248/yakushi.18-00091-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Skeletal muscle atrophy reduces quality of life and increases mortality. However, there are few available drugs for the treatment of muscle atrophy. Recently, cell signaling pathways involved in skeletal muscle atrophy or hypertrophy have been determined. To develop drugs for skeletal muscle atrophy, we have studied compounds which modulate pathways of myogenic differentiation, a pivotal step for the maintenance of skeletal muscle mass. First, we examined a K+ channel opener on myogenic differentiation, since hyperpolarization is a trigger for skeletal muscle differentiation. 5,6-Dichloro-1-ethyl-1,3-dihydro-2H-benzimidazol-2-one (DCEBIO), an opener of the small/intermediate conductance Ca2+ activated K+ (SKCa/IKCa) channels, increases myogenic differentiation in C2C12 mouse skeletal myoblasts. This effect was inhibited by TRAM-34, an IKCa channel blocker. This suggests that K+ channels in skeletal muscle stem cells are potential targets for an anti-muscle atrophy drug. Next, we searched for drugs which prevent sepsis-induced muscle atrophy. Lipopolysaccharide (LPS), an inducer of sepsis, attenuates myogenic differentiation in C2C12 myoblasts. LPS also increases the protein expression of myostatin and activates NFκB during differentiation. The TLR4 signal inhibitor TAK-242, and an anti-TNFα neutralizing antibody, reduce these inflammatory responses. Our data suggest that LPS inhibits myogenic differentiation via the NFκB/TNFα pathway. This pathway may be involved in the development of muscle wasting caused by sepsis.
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Affiliation(s)
- Kazuho Sakamoto
- Department of Pharmacology, School of Medicine, Fukushima Medical University
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3
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Abmayr SM, Balagopalan L, Galletta BJ, Hong SJ. Cell and molecular biology of myoblast fusion. INTERNATIONAL REVIEW OF CYTOLOGY 2003; 225:33-89. [PMID: 12696590 DOI: 10.1016/s0074-7696(05)25002-7] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
In organisms from Drosophila to mammals, the musculature is comprised of an elaborate array of distinct fibers that are generated by the fusion of committed myoblasts. These muscle fibers differ from each other in features that include location, pattern of innervation, site of attachment, and size. The sizes of the newly formed muscles of an embryo are controlled in large part by the number of cells that form the syncitial fiber. Over the past few decades, an extensive body of literature has described the process of myoblast fusion in vertebrates, relying primarily on the strengths of tissue culture model systems. More recently, genetic studies in Drosophila embryos have provided new insights into the process. Together, these studies define the steps necessary for myoblast differentiation, the acquisition of fusion competence, the recognition and adhesion between myoblasts, and the fusion of two lipid bilayers into one. In this review, we have attempted to combine insights from both Drosophila and vertebrate studies to trace the processes and molecules involved in myoblast fusion. Implicit in this approach is the assumption that fundamental aspects of myoblast fusion will be similar, independent of the organism in which it is occurring.
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MESH Headings
- Animals
- Cell Adhesion/physiology
- Cell Differentiation/physiology
- Cell Membrane/metabolism
- Drosophila melanogaster/embryology
- Drosophila melanogaster/metabolism
- Drosophila melanogaster/ultrastructure
- Embryo, Nonmammalian/embryology
- Embryo, Nonmammalian/metabolism
- Embryo, Nonmammalian/ultrastructure
- Humans
- Membrane Fusion/physiology
- Muscle Fibers, Skeletal/metabolism
- Muscle Fibers, Skeletal/ultrastructure
- Muscle, Skeletal/embryology
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/ultrastructure
- Myoblasts, Skeletal/metabolism
- Myoblasts, Skeletal/ultrastructure
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Affiliation(s)
- Susan M Abmayr
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA
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4
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Weston C, Gordon C, Teressa G, Hod E, Ren XD, Prives J. Cooperative regulation by Rac and Rho of agrin-induced acetylcholine receptor clustering in muscle cells. J Biol Chem 2003; 278:6450-5. [PMID: 12473646 DOI: 10.1074/jbc.m210249200] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
A key aspect of neuromuscular synapse formation is the clustering of muscle acetylcholine receptors (AChR) at synaptic sites in response to neurally secreted agrin. Agrin-induced AChR clustering in cultured myotubes proceeds via the initial formation of small microclusters, which then aggregate to form AChR clusters. Here we show that the coupling of agrin signaling to AChR clustering is dependent on the coordinated activities of Rac and Rho GTPases. The addition of agrin induces the sequential activation of Rac and Rho in C2 muscle cells. The activation of Rac is rapid and transient and constitutes a prerequisite for the subsequent activation of Rho. This temporal pattern of agrin-induced Rac and Rho activation reflects their respective roles in AChR cluster formation. Whereas agrin-induced activation of Rac is necessary for the initial phase of AChR cluster formation, which involves the aggregation of diffuse AChR into microclusters, Rho activation is crucial for the subsequent condensation of these microclusters into full-size AChR clusters. Co-expression of constitutively active forms of Rac and Rho is sufficient to induce the formation of mature AChR clusters in the absence of agrin. These results establish that Rac and Rho play distinct but complementary roles in the mechanism of agrin-induced AChR clustering.
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Affiliation(s)
- Christi Weston
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York 11794, USA
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5
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Kim SS, Kim JH, Lee SH, Chung SS, Bang OS, Park D, Chung CH. Involvement of protein phosphatase-1-mediated MARCKS translocation in myogenic differentiation of embryonic muscle cells. J Cell Sci 2002; 115:2465-73. [PMID: 12045217 DOI: 10.1242/jcs.115.12.2465] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Myristoylated alanine-rich C kinase substrate (MARCKS) translocates from the cytosol to the plasma membrane while mononucleated myoblasts fuse to form multinucleated myotubes. Here, we show that protein phosphatase-1-mediated dephosphorylation of MARCKS largely influences its subcellular localization and the fusion process. Treatment with okadaic acid or tautomycin, which are potent inhibitors of protein phosphatases and cell fusion, was found to reversibly block the MARCKS translocation. Moreover, the dephosphorylating activity against MARCKS markedly increased during myogenesis, and this increase was closely correlated with the membrane fusion of the cells. In addition, protein phosphatase-1 was identified as a major enzyme that is responsible for dephosphorylation of MARCKS. Furthermore, a mutation preventing MARCKS phosphorylation and thus facilitating MARCKS translocation resulted in promotion of the cell fusion. In contrast, overexpression of MARCKS carrying a mutation that blocks myristoylation and thus prevents the MARCKS translocation impaired the myoblast fusion. Together with the fact that MARCKS regulates the cytoskeleton dynamics by crosslinking the actin filaments in the plasma membrane and that myoblast fusion accompanies massive cytoskeleton reorganization, these results suggest that protein phosphatase-1-mediated MARCKS localization at the membrane is required for the fusion of embryonic muscle cells.
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MESH Headings
- Amino Acid Sequence/drug effects
- Amino Acid Sequence/genetics
- Animals
- Cell Adhesion/drug effects
- Cell Adhesion/genetics
- Cell Differentiation/drug effects
- Cell Differentiation/physiology
- Cell Membrane/drug effects
- Cell Membrane/metabolism
- Cells, Cultured
- Chick Embryo
- Creatine Kinase/metabolism
- Cytosol/drug effects
- Cytosol/metabolism
- Enzyme Inhibitors/pharmacology
- Intracellular Signaling Peptides and Proteins
- Membrane Proteins
- Muscle Fibers, Skeletal/cytology
- Muscle Fibers, Skeletal/drug effects
- Muscle Fibers, Skeletal/enzymology
- Muscle, Skeletal/cytology
- Muscle, Skeletal/embryology
- Muscle, Skeletal/enzymology
- Mutation/drug effects
- Mutation/genetics
- Myoblasts, Skeletal/cytology
- Myoblasts, Skeletal/drug effects
- Myoblasts, Skeletal/enzymology
- Myosin Heavy Chains/metabolism
- Myristoylated Alanine-Rich C Kinase Substrate
- Okadaic Acid/pharmacology
- Phosphoprotein Phosphatases/drug effects
- Phosphoprotein Phosphatases/metabolism
- Phosphorylation/drug effects
- Protein Phosphatase 1
- Protein Transport/drug effects
- Protein Transport/physiology
- Proteins/drug effects
- Proteins/genetics
- Proteins/metabolism
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Affiliation(s)
- Sang Soo Kim
- NRL of Protein Biochemistry, School of Biological Sciences, Seoul National University, 56-1 Shinreem-dong, Kwanak-gu, Seoul 151-742, Korea
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6
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Affiliation(s)
- E Cooper
- Department of Physiology, McGill University, Montreal, Quebec H3G 1Y6, Canada.
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Bijlenga P, Liu JH, Espinos E, Haenggeli CA, Fischer-Lougheed J, Bader CR, Bernheim L. T-type alpha 1H Ca2+ channels are involved in Ca2+ signaling during terminal differentiation (fusion) of human myoblasts. Proc Natl Acad Sci U S A 2000; 97:7627-32. [PMID: 10861024 PMCID: PMC16596 DOI: 10.1073/pnas.97.13.7627] [Citation(s) in RCA: 148] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mechanisms underlying Ca(2+) signaling during human myoblast terminal differentiation were studied using cell cultures. We found that T-type Ca(2+) channels (T-channels) are expressed in myoblasts just before fusion. Their inhibition by amiloride or Ni(2+) suppresses fusion and prevents an intracellular Ca(2+) concentration increase normally observed at the onset of fusion. The use of antisense oligonucleotides indicates that the functional T-channels are formed by alpha1H subunits. At hyperpolarized potentials, these channels allow a window current sufficient to increase [Ca(2+)](i). As hyperpolarization is a prerequisite to myoblast fusion, we conclude that the Ca(2+) signal required for fusion is produced when the resting potential enters the T-channel window. A similar mechanism could operate in other cell types of which differentiation implicates membrane hyperpolarization.
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Affiliation(s)
- P Bijlenga
- Département de Physiologie, Centre Médical Universitaire, and Division de Recherche Clinique Neuro-Musculaire, Hôpital Cantonal Universitaire, CH-1211 Geneva 4, Switzerland
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8
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Lobo MV, Santander RG, Cuadrado GM, Alonso FJ. Cytochemical localization of calcium in prefusion myoblasts from the chick embryo myotome. THE HISTOCHEMICAL JOURNAL 1999; 31:347-55. [PMID: 10462221 DOI: 10.1023/a:1003744007153] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Myoblast fusion is a Ca2+-dependent process. The aim of this report was to study the localization of Ca2+ in prefusion myoblasts from the brachial somites of chick embryos (51-108 h of incubation), using the potassium pyroantimonate cytochemical method. When observed under a transmission electron microscope, electron-dense precipitates of Ca2+-antimonate were found in the basement membrane of the myotome, which separates the myotome from the adjacent mesenchyma. Within myoblasts, triads and sarcoplasmic reticulum associated with the first newly formed sarcomeres were observed, but a T-tubule network was not found. Moreover, Ca2+-antimonate precipitates were not observed in structures resembling T-tubules or sarcoplasmic reticulum. The results suggest that sarcomerogenesis and sarcoplasmic reticulum development occur simultaneously and that prefusion myoblasts have neither a T-tubule network nor Ca2+ deposits on sarcoplasmic reticulum. Small Ca2+ pools were found in the myoblast nuclei, cytoplasmic vesicles and mitochondrias. Ca2+-antimonate precipitates periodically distributed at the cell periphery, close to the cell membrane, were observed. These precipitates could represent internal Ca2+ stores located in the peripheral couplings and it is proposed that these pools of Ca2+ could be mobilized before fusion, leading to the increase in free intracellular Ca2+ that precedes myoblast fusion.
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Affiliation(s)
- M V Lobo
- Department of Morphological Sciences and Surgery, University of Alcala, Madrid, Spain
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9
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Rochard P, Cassar-Malek I, Marchal S, Wrutniak C, Cabello G. Changes in mitochondrial activity during avian myoblast differentiation: influence of triiodothyronine or v-erb A expression. J Cell Physiol 1996; 168:239-47. [PMID: 8707859 DOI: 10.1002/(sici)1097-4652(199608)168:2<239::aid-jcp2>3.0.co;2-q] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Numerous data suggest that mitochondrial activity is involved in the regulation of cell growth and differentiation. Therefore, we have studied the changes in mitochondrial activity in avian myoblast cultures (QM7 line) undergoing differentiation or in BrdU-treated, differentiation-deficient cells. As we have previously shown that triiodothyronine and v-erb A expression stimulate myogenic differentiation, we have also observed their influence upon mitochondrial activity. Comparison of control and BrdU-treated myoblasts indicated that precocious differentiation events were associated with a stimulation of citrate synthase and cytochrome oxidase activities. They also induced a transient decrease in mitochondrial membrane potential assessed by rhodamine 123 uptake. In control myoblasts, a general stimulation of mitochondrial activity was recorded at cell confluence, prior to terminal differentiation. These events did not occur in BrdU-treated myoblasts, thus indicating that they were tightly linked to myoblast commitment. Whereas no significant triiodothyronine influence could be detected upon mitochondrial activity, we observed that v-erb A expression significantly depresses the mitochondrial membrane potential in control myoblasts. This action was not observed in BrdU-treated myoblasts, thus suggesting that it involves an indirect pathway linked to differentiation. Moreover, the oncoprotein abrogated the decrease in E2-PDH subunit level observed at cell confluence. These data underline that changes in mitochondrial activity occurred prior to myoblast terminal differentiation and could be involved in the processes regulating myogenesis. In addition, they provide the first evidence that the v-erb A oncoprotein influences mitochondrial activity.
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Affiliation(s)
- P Rochard
- Laboratoire de Différenciation Cellulaire et Croissance, INRA-ENSA, Montpellier, France
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10
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Moody WJ, Simoncini L, Coombs JL, Spruce AE, Villaz M. Development of ion channels in early embryos. JOURNAL OF NEUROBIOLOGY 1991; 22:674-84. [PMID: 1722507 DOI: 10.1002/neu.480220703] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- W J Moody
- Department of Zoology, University of Washington, Seattle 98195
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11
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Kim HS, Chung CH, Kang MS, Ha DB. Okadaic acid blocks membrane fusion of chick embryonic myoblasts in culture. Biochem Biophys Res Commun 1991; 176:1044-50. [PMID: 2039488 DOI: 10.1016/0006-291x(91)90388-n] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Okadaic acid was found to block membrane fusion of chick embryonic myoblasts in culture. It also induced morphological change of the cells from bipolar to spherical shape. These effects were dose-dependent, and could be reversed upon removal of the drug from the culture medium. It showed, however, no effect on the induction of muscle specific proteins including tropomyosin and creatine kinase. When okadaic acid was treated to the cell lysates, the phosphorylation state of many proteins significantly increased. These results suggest that the inhibition of myoblast fusion by okadaic acid may be mediated by the increase in the phosphorylation of certain, unknown protein(s) that regulate the fusion process.
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Affiliation(s)
- H S Kim
- Department of Molecular Biology, College of Natural Sciences, Seoul National University, Korea
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12
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Abstract
Factors which effect proliferation and fusion of muscle precursor cells have been studied extensively in tissue culture, although little is known about these events in vivo. This review assesses the tissue culture derived data with a view to understanding factors which may control the regeneration of mature skeletal muscle in vivo. The following topics are discussed in the light of recent developments in cell and molecular biology: 1) Injury and necrosis of mature skeletal muscle fibres 2) Phagocytosis of myofibre debris 3) Revascularisation of injured muscle 4) Activation and proliferation of muscle precursor cells (mpc) in vivo Identification of mpcs; Satellite cell relationships; Extracellular matrix; Growth factors; Hormones; Replication. 5) Differentiation and fusion of muscle precursor cells in vivo Differentiation; Fusion; Extracellular matrix; Cell surface molecules: Growth factors and prostaglandins 6) Myotubes and innervation.
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Affiliation(s)
- M D Grounds
- Department of Pathology, University of Western Australia
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