Abstract
In skeletal myoblasts, Ras has been considered to be a strong inhibitor of myogenesis. Here, we demonstrate that Ras is involved also in the chemotactic response of skeletal myoblasts. Expression of a dominant-negative mutant of Ras inhibited chemotaxis of C2C12 myoblasts in response to basic fibroblast growth factor (bFGF), hepatocyte growth factor (HGF), and insulin-like growth factor 1 (IGF-1), key regulators of limb muscle development and skeletal muscle regeneration. A dominant-negative Ral also decreased chemotactic migration by these growth factors, while inhibitors for phosphatidylinositol 3-kinase and mitogen-activated protein kinase kinase (MEK) showed no effect. Activation of the Ras-Ral pathway by expression of an activated mutant of either Ras, the guanine-nucleotide dissociation stimulator for Ral, or Ral resulted in increased motility of myoblasts. The ability of Ral to stimulate motility was reduced by introduction of a mutation which prevents binding to Ral-binding protein 1 or phospholipase D. These results suggest that the Ras-Ral pathway is essential for the migration of myoblasts. Furthermore, we found that Ras and Ral are activated in C2C12 cells by bFGF, HGF and IGF-1 and that the Ral activation is regulated by the Ras- and the intracellular Ca(2+)-mediated pathways. Taken together, our data indicate that Ras and Ral regulate the chemotactic migration of skeletal muscle progenitors.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Butadienes / pharmacology
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Calcimycin / pharmacology
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Calcium / metabolism
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Cell Line
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Cell Movement / drug effects
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Cell Movement / genetics
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Chemotaxis / drug effects
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Chemotaxis / physiology*
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Chromones / pharmacology
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Egtazic Acid / analogs & derivatives
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Egtazic Acid / pharmacology
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Enzyme Inhibitors / pharmacology
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Extracellular Matrix Proteins / chemistry
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Extracellular Matrix Proteins / metabolism
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Genes, ras
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Growth Substances / pharmacology
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Insulin-Like Growth Factor I / metabolism
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Insulin-Like Growth Factor I / pharmacology
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Isopropyl Thiogalactoside / pharmacology
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MAP Kinase Kinase Kinase 1*
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Mice
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Morpholines / pharmacology
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Muscle, Skeletal / cytology*
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Muscle, Skeletal / metabolism*
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Nitriles / pharmacology
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Phosphatidylinositol 3-Kinases / metabolism
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Phosphoinositide-3 Kinase Inhibitors
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Protein Serine-Threonine Kinases / antagonists & inhibitors
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Protein Serine-Threonine Kinases / metabolism
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Signal Transduction
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ral GTP-Binding Proteins / genetics
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ral GTP-Binding Proteins / metabolism*
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ras Proteins / genetics
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ras Proteins / metabolism*
Substances
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Butadienes
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Chromones
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Enzyme Inhibitors
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Extracellular Matrix Proteins
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Growth Substances
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Morpholines
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Nitriles
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Phosphoinositide-3 Kinase Inhibitors
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U 0126
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1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester
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2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
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Isopropyl Thiogalactoside
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Calcimycin
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Egtazic Acid
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Insulin-Like Growth Factor I
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Protein Serine-Threonine Kinases
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MAP Kinase Kinase Kinase 1
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Map3k1 protein, mouse
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ral GTP-Binding Proteins
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ras Proteins
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Calcium