title: Identification of MAFbx as a myogenin-engaged F-box protein in SCF ubiquitin ligase.
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.
authors.affiliation: Department of Biology, Graduate School of Science, Chiba University, Inage-ku, Chiba, Japan.
authors.forename: Misako
authors.initials: M
authors.lastname: Jogo
authors.forename: Seiji
authors.initials: S
authors.lastname: Shiraishi
authors.forename: Taka-aki
authors.initials: TA
authors.lastname: Tamura
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D003907:Dexamethasone / Q000378:metabolism; D005938:Glucocorticoids / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D032446:Myoblasts / Q000166:cytology / Q000502:physiology; D018008:Myogenin / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D044843:SKP Cullin F-Box Protein Ligases / Q000235:genetics / Q000378:metabolism*
chemical_list: D005938:Glucocorticoids; D009124:Muscle Proteins; C503801:Myog protein, mouse; D018008:Myogenin; D011993:Recombinant Fusion Proteins; D007334:Insulin-Like Growth Factor I; D003907:Dexamethasone; C486691:Fbxo32 protein, mouse; D044843:SKP Cullin F-Box Protein Ligases