Abstract
Myogenesis is conducted by transcription factors including MyoD and myogenin. Myogenin is known to be polyubiquitinated by SCF (Skp1/Cullin 1/F-box protein) followed by proteasomal degradation, though the participating F-box protein is remaining unidentified. In this study, we found that myogenin in differentiated myoblasts is destabilized by muscle atrophy-inducing dexamethasone and that MAFbx (muscle atrophy F-box protein) is increased in atrophying myotubes. MAFbx overexpression resulted in MG132-sensitive reduction of myogenin. Myogenin had a MAFbx-recognition motif and interacted with MAFbx. MAFbx activated polyubiquitination of myogenin. The results of this study suggest that MAFbx functions as an F-box protein for ubiquitination of myogenin.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Cell Line
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Dexamethasone / metabolism
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Glucocorticoids / metabolism
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Insulin-Like Growth Factor I / metabolism
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Mice
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Molecular Sequence Data
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Muscle Proteins / genetics
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Muscle Proteins / metabolism*
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Myoblasts / cytology
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Myoblasts / physiology
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Myogenin / genetics
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Myogenin / metabolism*
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RNA Interference
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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SKP Cullin F-Box Protein Ligases / genetics
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SKP Cullin F-Box Protein Ligases / metabolism*
Substances
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Glucocorticoids
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Muscle Proteins
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Myog protein, mouse
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Myogenin
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Recombinant Fusion Proteins
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Insulin-Like Growth Factor I
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Dexamethasone
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Fbxo32 protein, mouse
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SKP Cullin F-Box Protein Ligases